onion, finely chopped
salt and pepper, to taste
Soak tomatillos in bowl of cold water to loosen husks. Drain and peel off husks.
Place tomatillos, onions, peppers, and garlic in saucepan with water to cover halfway. Bring to a boil until soft, about 10 minutes. Drain.
Transfer mixture to blender and blend to puree.
Heat 2 tablespoons vegetable oil (do not substitute) in saucepan over medium heat. Add puree mixture.
Season to taste with salt and pepper. Bring to boil and then reduce to simmer for about 5 minutes.