1-3 serrano peppers
3-4 tomatillos
2-4 cloves garlic
3-5 tomatoes, fresh or canned.
1/2 cup cilantro
salt
juice from one lime or lemon
Toast peppers (put them on a hot skillet, turning them as they blister, until they are evenly blistered). Remove papery outer skin of tomatillos and simmer until they turn from green to yellowish olive green (about 5 minutes).
Mash or blend garlic cloves. Add the peppers and the tomatillos. Add tomatoes. Add cilantro. Add salt and lime or lemon juice to taste.
Variations: add 1/2 onion. Use a blend of hot peppers (jalapanos, thai). If you remove the seeds after toasting the peppers, they won't be as hot. In general, the smaller the chile, the hotter it is.