two you sautee the whole chilies and the tomatillos in generous amounts of oil and then blend in a blender with water and salt,
three you roast chilies and tomatillos, blend them with some water in a blender with salt and garlic then toss it with minced onion and cilantro.
I use the SUPERIOR "Tomatillo Milpero" which is a really tiny berry version of "Tomatillos" it is superior in taste and makes a better sauce it is also more expensive sometimes to expensive for our budget so we end up using regular large "Tomatillos" but this time we bought "Tomatillo Milpero"
Today I did it the third way which is my preferred way.
-6-7 Serrano Chilies
-2 cups "tomatillo milpero"
-1 clove garlic
-½ cup minced cilantro
-¼ of a minced onion
-salt to taste about 1-2 teaspoons
-some water to help blend sauce not to much
-Cover a griddle top with aluminum foil and heat on medium. Or simply use a pan and cover with top with some foil for easy clean up later (TRUST ME BECAUSE YOU WILL END UP WITH HARD TO REMOVE BLACK CRUST ON THE PAN OR GRIDDLE IF YOU DON'T)
-Lay the tomatillos and Serrano chilies until blackened and roasted set aside
-Remove the black parts from the chilies with a wet towel or napkind. Remove the chilies tops
-Throw in a blender with one peeled garlic clove and salt to taste with a small amount of water, blend to a sauce
-Pour in a bowl
-Mix in the cilantro and onion and you are done.