Roasted Tomatoes for Sauce: 95% of you have never considered one of these roasting methods!

By Jeanie Rose | Tomatoes

Jul 02

Roasted Tomatoes for Sauce: 95% of you have never considered one of these roasting methods!If you have a tomato bounty, the tomato roasting method is ideal for processing those tomatoes that are undersized, misshapen or a bit too soft for salad or sandwich. All that is necessary is to wash them well and cut out the stem caps. There is no need to peel or seed your tomatoes. In fact, that tomato skins and seeds will add a great deal of flavor to the final product — rich roasted tomatoes or a tomato sauce.

Roasted tomatoes end up nearly sauce-like before they are done. Here I describe how to take a raw tomato and turn it into sauce via roasting but do experiment with all stages of the roasted tomato. Use roasted tomatoes whole in other kitchen creations.

I outline a method for roasting in the oven and in the crock pot. Oven roasted tomatoes produce a more flavorful product but they will heat up your kitchen. Crock pot roasted tomatoes may be a better fit for your circumstances. It is the only reasonable solution in our 100-degree kitchen in the summer.

Oven Roasted Tomatoes — Fast or Slow Roasted

Roasted Tomatoes for Sauce: 95% of you have never considered one of these roasting methods!Oven roasted tomatoes are a stand-out for flavor but the downside is that they require an oven. If your kitchen is piping hot in the summer, this may not be your best option. If your kitchen temperature is not a consideration, by all means, use this method to roast your tomatoes.

These roasted tomatoes can be canned or frozen to enjoy the headiness of summer tomatoes in the dead of winter. They will require about half the space of non-roasted tomatoes because so much of the moisture has evaporated. With this method, there is no need to peel or seed your tomatoes, saving you a great deal of time.

The ingredients listed below are just a suggestion. Use whatever amounts of tomato, onion, and garlic you have available. Use herbs that you generally love to use with tomatoes. Include the herbs with a light hand in the first batch you make. After tasting the finished product, you will better judge how much for the next batch.

One thing to be aware of is that tomatoes roast better if they are not piled two and three deep in the roasting pan so that they roast rather than stew. It is the roasting that caramelizes the sugars that provide the amazing flavor.

Oven Roasted Tomato Ingredients

Roasted Tomatoes for Sauce: 95% of you have never considered one of these roasting methods!

  • About 20 medium sized ripe tomatoes
  • 1 large onion diced
  • 6 cloves garlic, minced
  • 1 jalapeño pepper, washed and stemmed
  • 3-4 tablespoons olive oil
  • 1 1/2 teaspoons sea salt
  • 2 teaspoons fresh oregano or 1/2 teaspoon dried oregano
  • 1 teaspoon fresh tarragon or 1/4 teaspoon dried tarragon

Oven Roasted Tomato Steps

Roasted Tomatoes for Sauce: 95% of you have never considered one of these roasting methods!

  1. Wash the tomatoes and cut out the stem end. Cut the tomatoes in quarters and toss them into a large roasting pan. Do not pile them up. Use two pans if necessary or roast the tomatoes in two batches.
  2. If you want a minimum hot kick in your tomatoes, then remove the seeds and pulp before adding the jalapeno to the tomato mix.
  3. Add the onions, garlic, seasonings, salt and oil.
  4. Toss gently but thoroughly. You want the tomatoes to be completely coated with oil.
  5. Roast the tomatoes slowly at 275 degrees or a shorter roast at 375 degrees. I prefer the slower roast. The flavor is a bit more developed and you need not be so concerned about burning the tomatoes.
  6. Check the tomatoes from time to time and give them a good stir to ensure even roasting. A slow roast can take up to 4 hours. A quick one will take about 45 minutes.
  7. When the tomatoes start smelling really wonderful, they are ready for use. I continue past this point in the roasting in order to cook the tomatoes down more and evaporate more of the liquid. The resulting roast is a perfect base for a number of my recipes. Roast to your own liking.
  8. Serve the roasted tomatoes as a side dish or let them cool and run them through a food processor or puree them with an immersible blender. The resulting tomato sauce is thick and delectable.
  9. Can or freeze your sauce if you do not use it all up in a few short days.

I love this idea for preserving tomatoes. Often I have a couple dozen tomatoes, perfect for this project. Seldom do I have 2 bushels that make it worth the trouble of canning. If you are going to freeze the sauce, consider freezing in measured amounts to use in specific recipes.

Crock Pot Roasted Tomatoes

Because of the simplicity of this method and the lack of air conditioning in our 100-year-old house, we favor this method in our own home. After testing this plan on one pot of tomatoes, we keep 2-3 crock pots going through the tomato harvest and it has become my go-to preservation method for tomatoes. Here are some reasons I love roasting tomatoes in a crock pot:

  • There is no need to peel or seed the tomatoes, saving your precious time. There is no need to lose tomatoes because you lack the time for processing. This is quick and easy.
  • The sugars in the tomatoes begin to caramelize, adding a rich flavor to the tomatoes that you seldom experience with other methods of dealing with tomatoes. This is the kind of flavor you may enjoy in a fine Italian restaurant.
  • Add other ingredients and seasonings that will produce a rich sauce base for some of your favorite dishes: pasta sauce, enchilada sauce, tomato soup, hot salsas. Include onion and garlic, sweet peppers, hot peppers. If your ultimate goal is something Italian then go with basil and oregano. If you’re going Mexican, then include fresh cilantro, toasted crushed cumin seed, and some powdered coriander. Developing your own signature sauces is artistic fun. You could even can pint jars of your finest sauce creation to give as gifts.
  • Much of the liquid content in this sauce is evaporated so the tomato sauce takes up just a fraction of the space it required before cooking. This is significant for storage whether you freeze the sauce or can it. Our sauce gets frozen. There is never enough at one time to make it worth the mess of canning two or three jars.
  • With the crock pot plan you can cook on the back porch or the front deck. Save your kitchen from heating up any more than it already is. Roasting tomatoes in the oven produces a slightly tastier product but the heat can be a deal-breaker. Back porch cooking is the answer the only problem is that if you have neighbors nearby, they will want to come to dinner. The aroma of these cooking tomatoes is tantalizing. Pass on your secret sauce savvy. The neighbors will love you for it.

The following recipe and list of ingredients is really a suggestion. If you added nothing to your tomatoes but some oil, salt, and pepper, they would still be far more tasty than anything you can purchase.

Crock Pot Roasted Tomato Ingredients

Roasted Tomatoes for Sauce: 95% of you have never considered one of these roasting methods!

  • 20 ripe garden tomatoes: a paste-type tomato will develop its best flavor as it cooks
  • 1 large onion
  • 5 large garlic cloves
  • 5 sweet peppers such as sweet banana or sweet Italian
  • 1 jalapeño pepper
  • 2 teaspoon sea salt and 1 teaspoon freshly ground pepper
  • 3 tablespoons olive oil
  • Herbs of choice – Use no more than three and then with a light hand. After you make a batch or two of this tomato sauce you will have a better idea of which herbs you like best and how much to use. Some suggestions: basil, parsley, oregano, rosemary, cilantro, cumin, coriander, chili powder, etc.

Crock Pot Roasted Tomato Steps

  1. Wash all the vegetables and let them drain. Even the most stunning tomatoes and peppers have a light coating of dust. Dust is not a flavor enhancer. Get rid of it.
  2. Cut the stem ends from the tomatoes; quarter the tomatoes; toss into a large crock pot.
  3. Peel and cube the onion into 1/2 inch pieces. Add to the pot.
  4. Peel the garlic. There is no need to mince or slice.
  5. Remove the stem ends and seeds from the sweet peppers. If you leave the seeds in, they impart a bitterness that most people do not enjoy. Cut the peppers into 1/2 inch rings and place in the crock pot.
  6. Remove the stem end from the jalepeño. If you want more heat, keep the seeds inside. If not, remove the seeds carefully. Handling hot peppers is an art in itself.
  7. Add the salt, pepper, oil, and herbs. Stir well. Attempt to coat all the tomato pieces with oil.
  8. Set the crock pot on high and leave at that setting until the mix reaches a simmer. Keep the pot uncovered without a lid.
  9. Once it reaches a simmer, lower the setting. Place the lid to partially cover the pot. You want the steam to escape.
  10. Cook time will vary depending on the size of your pot and they way your pot operates. We have one pot that takes about 1/3 more time to do the same job. A large pot can go for 12 to 14 hours without risking burning anything.
  11. Cook until your tomatoes reach your desired consistency. You may choose to have juicier sauce or thick pasty sauce. It’s your call. Do stir up the contents of your pot a few times during this cook session. The thick sauce just takes more time. Most of what I do is thick. It takes less room in the freezer and can be watered down with bone broth or cream in my favorite recipes. You’ll discover your own way with this.
  12. If the tomatoes overcook, they will begin to burn.
  13. Once they are done, run your tomato sauce through a food processor or use an immersible blender. Almost instantly you have a homogenous sauce. No one will ever notice that you did not peel or seed the tomatoes, mince the garlic, or finely chop the onions and peppers.

You will want to use some of this sauce immediately because the tantalizing aroma will dry you crazy if you don’t. Freeze whatever amount of sauce is extra in workable amounts so you can enjoy this delicious flavor all winter long.

Roasted Tomatoes

This is our basic approach to oven roasted tomatoes


  • 20 units tomatoes, medium
  • 1 unit onion, large diced
  • 6 cloves garlic minced
  • 1 unit jalapeno pepper de-stemmed
  • 4 tbsp olive oil
  • 1 1/2 tsp salt
  • 2 tsp oregano fresh
  • 1 tsp tarragon fresh


  • Wash the tomatoes and remove the stem end.
  • Quarter the tomatoes and place them in a roasting pan. Do not overcrowd them!
  • Add the jalapeno, removing the seeds if you seek a more mild tomato product.
  • Add the onions, garlic, seasonings, salt and oil.
  • Toss the ingredients together in the pan. Spread them out.
  • Roast the tomatoes slowly at 275 degrees or a shorter roast at 375 degrees. (We prefer a slow roast.)
  • Stir the tomatoes every 20 minutes or so, checking for doneness. Fragrance will be your best indicator -- these things smell great as they are finishing up!
  • A slow roast may take 4 hours. A quick roast may only take 45 minutes.
Tried this recipe?Let us know how it was!
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11 years ago

I thoucht you can’t safely can recipes with Oil in them?

Amanda Rose
11 years ago
Reply to  Joli

That’s a good question, Joli. I’ll get clarification.

Amanda Rose
11 years ago
Reply to  Joli

I’m here with my mom who says she’s always done it, so I looked it up. The big issue for this recipe seems to be the pH. I have no idea if this combination ends up in a safety zone, so I will have to check one of these batches and get back to you. In the meantime, the safe strategy is to roast your tomatoes without the oil and without the other vegetables and then can them. It is still a very big time saver over other methods, it just won’t taste quite as good (as is the case… Read more »

11 years ago

I would also like to know if either of these recipes can be canned. I don’t have the freezer space but love the sound of these recipes.

11 years ago

an alternative to the oven is the barbecue .. it gives them a slight smoky flavor that enhances the tomato and onions/garlic flavor..I do not use any oil and after I puree it I either freeze it or if a big batch I bring to a boil and can it.


[…] roasted tomatoes are more your […]

10 years ago

I freeze until I have enough for sauce making via canning; once they start to thaw, the skins slip easily. However, this method sounds easier still since the roasted skins just end up in the sauce – both saving work and adding flavor – I can “taste” this in my imagination, and it’s a deeper flavor than what I usually do. Having just sat here last night peeling about 15 gallons of slightly thawed tomatoes, I wish I’d run across this idea first! My fingers got cold! Especially the crockpot/immersion blender method – I love that. Next year, I am… Read more »

10 years ago

As for the canning issue, my rule of thumb is either add lemon juice or ascorbic acid for water-bath canning to make sure it’s acidic enough to avoid botulism growth or just go ahead and pressure can. The advantage of pressure canning is you don’t have to add the acid which changes the flavor, but things do cook longer than you might have wanted (though it’s hard to overcook sauce, but other recipes I often cut the cooking time way back if I’m going to pressure can). Different varieties of tomatoes have different acidities, you need the sauce at a… Read more »

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