MAKES ABOUT 1 CUP
Combine the cilantro, garlic, chili, and walnuts in a blender or food
processor.
Add 1/3 cup liquid, 1 teaspoon salt, pepper, cumin (if using) and process
to a smooth paste.
Add enough water to obtain a pourable paste.
Taste for seasoning, adding salt and lemon juice as necessary; the sauce should
be highly seasoned.
Makes about 1 cup.