For years and years I've been trimming my garden basil, freezing it, and then using the basil all winter in soup, stew, and pasta sauce, and this post has all my tips for successfully freezing basil. [from KalynsKitchen.com]
Surprisingly, both cilantro and basil freeze very well. After cutting the leaves, preferably in the early morning while they are freshest, we mix them with a small amount of olive oil... just enough to coat the leaves. They are then packed into freezer bags and frozen for later use. The olive oil makes it really easy to separate the frozen leaves and also adds an extra flavor to the mix.