Freezing cilantro is the best way to preserve its flavor. This is the method that has worked best for us.
Wash your cilantro well, following detailed instructions above.
Allow cilantro to drain in a large colander.
Rough chop the cilantro.
Blend cilantro and olive oil in a blender until pureed.
Place cilantro puree in ice cube trays or baggie.
Place cilantro puree until frozen.
Place cilantro cubes in freezer storage baggie for long-term storage.