Because this paste is so versatile, it’s handy to have a stash of cilantro roots in the freezer. Simply chop the roots and wash and store them in a plastic bag in the freezer. You don’t need to defrost them before using, as they can be chopped and pounded still frozen. And if you just can’t lay your hands on the roots, cilantro stems (minus the leaves) can easily stand in for the roots.