Salsa Verde

Combine all ingredients in a saucepan. Bring to a boil, lower the heat to a bare simmer, and cover. Let it simmer, stirring occasionally, for 40 - 50 minutes. This will cook down tremendously, to about 1/3 its initial volume. Very tasty on enchiladas, or used as a dip for chips, it will also keep for about a week, tightly covered, and refrigerated. (Sauce will discolor to a darker green after a few hours, but the flavor is not adversely affected.) Note that it is fairly spicy, but doesn't have to be -- I once made this without using any chilis or cayenne, and found it quite flavorful that way, too.