A simple sauce of roasted tomatillos and chile de arbol that is excellent on burritos and similar things. This doesn't have to be spicy, but it's at its best when quite spicy.
10 large ripe tomatillos, outer skin removed and quartered
Chile de arbol to taste, ground (4-5 makes for moderate heat)
1 1/2 t cumin
2-3 cloves dry roasted garlic *see note
salt to taste
ground black pepper
50/50 mix of lime juice and cider or white vinegar to taste
Broil the tomatillos until they start to develop black spots, then transfer to a blender along with any juices they gave off. Add in the chile de arbol, the cumin, and the garlic. Blend together (you may have to add a little stock or water to get the right consistency). Add the salt, pepper, and vinegar mix; taste and adjust as necessary.
Note: dry roasting garlic involves heating it, skin on, in a cast iron skillet over medium until dark spots have formed on the skin on all sides. Remove from the skillet, remove the skin, and use as normal.