See Substitutions. Have the measure of broth ready. Cook fresh serrano or jalapeno peppers in boiling salted water until tender ~ about 5 minutes. (NOTE - If using fresh tomatillos, cook them with chiles.) Place tomatillos and chiles in a blender or food processor, along with cilantro, onion, and garlic. Stir. Process until smooth, but retain a little texture. See TIP! Heat oil in a medium-large non-stick skillet set over medium-high heat. When oil is hot -- enough to make a drop of the puree sizzle sharply -- pour the tomatillo mixture in the skillet all at once and stir constantly for 4 to 5 minutes, until mixture becomes darker and thicker. Add broth, return to a boil, reduce the heat to medium and simmer until thick enough to coat a spoon, about 10 to 15 minutes. Season with salt, as needed. Makes 2 cups. Use as an ingredient, a sauce, a salsa, etc. __________ TIP! Transfer the contents of the blender or food processor to an "easy-to-handle" bowl. SUBstitutions Fresh tomatillos = two 13-oz cans of tomatillos; Fresh chile peppers = up to 1 tablespoon diced, canned peppers; 3 Serrano peppers = 2 jalapenos. Drain canned ingredients NOTES : Taste the chile peppers. Sometimes serranos are hotter than jalapenos. The shelf-life is short - refrigerate up to 4 days.