Cilantro (coriander) is a versatile herb that is essential in many Mexican, Middle-eastern, and Indonesian style recipes. But it is almost always used fresh because it doesn't dry well. It also doesn't keep fresh for very long.
Here are some ways to extend its life in your kitchen so that you will always have its bright flavor on hand (and never again need to throw out wilted cilantro sprigs that you didn't use up in time).
Freezing Cilantro a.k.a. Coriander
If you simply stick a bunch of fresh cilantro into the freezer it will be discolored and mushy when it thaws. Yuck. The reason for this is that enzymes that decompose fresh plant material can survive freezing temperatures and work on the food even while it is in the freezer.
Fortunately, there is a way to freeze fresh cilantro so that it keeps its emerald green color and lovely flavor. You just have to blanch it first.
Blanching kills off those decomposing enzymes. To blanch fresh cilantro/coriander, bring a large pot of water to a boil. Have a big bowl of ice water ready.
Once the water is boiling, dip your bunch of cilantro into it just until it wilts. This shouldn't take more than a few seconds. You don't want to cook out the flavor of the herb, just kill off those decomposing enzymes.
As soon as the cilantro has wilted, immediately transfer it to the ice water. This eliminates the residual heat that would otherwise continue to cook it.
Pat the blanched cilantro dry. Strip the leaves off the stems and transfer to freezer bags and freeze. Tip: spread the leaves thinly in the bags and store flat. This will enable you to break off just what you need when you want to use some - but not all - of a bag of frozen herbs.
Freezing Cilantro Oil or Pesto
The blanching method above is the first step to ensuring your cilantro oil or pesto comes out of the freezer with the same vibrant color and taste that freshly made pesto or herbal oil has.
After you've blanched, chilled, and patted your cilantro sprigs dry, coarsely chop them, tender stems and all. Put them in a blender or food processor and puree, adding enough extra-virgin olive oil to make a smooth, somewhat liquid paste.
You can also use the blanched leaves to make your favorite pesto recipe before freezing.
If you just dump your oil or pesto into a big freezer container and freeze it, you'll have to take out the whole brick of pesto or oil and use it within a week. Better is to freeze it in small containers, or even better use one of the following two methods.
Freezing Pesto or Herbal Oil in Freezer Bags
Pour or spoon your oil or pesto into freezer bags. Put in just enough to cover the surface of the bag when it is horizontal. Freeze flat (horizontal). What you'll end up with is a pesto "pancake" from which you can break off just what you need (thank you, Barbara Kingsolver, for this tip).
Freezing Pesto or Herbal Oil in Freezer Containers
Alternatively, fill ice cube trays with your cilantro oil or pesto. Freeze, then pop out the cubes and transfer them to freezer containers (or freezer bags). Each cube will be approximately 1 tablespoon of herbal oil or pesto.
To make cilantro butter, use 1/4 cup of finely chopped fresh cilantro leaves in this basic herb butter recipe.
Finely chop a bunch of fresh cilantro. I include the stems and take some help from the food processor to mince them. Measure the chopped cilantro by loosely packing it into a measuring cup. For every 4 parts fresh, chopped cilantro (by volume), add 1 part kosher or other coarse, non-iodized salt. Mix well and store in tightly covered glass jars in the refrigerator for up to 1 year. Use anywhere cilantro flavor is welcome, leaving out any other salt called for in the recipe.