Preparation / Directions:
In a saucepan, heat the oil. Add the onions, jalapenos, Serranos, and garlic, and cook them over low heat until soft. Add everything else, cover the pan, and simmer 40 minutes. Allow the mixture to cool to room temperature.
Strain out the remaining solids, liquefy them in a food processor, and add them back to the strained liquid, stirring thoroughly. Set the sauce aside for several hours before serving to permit flavors to blend. Refrigerate the sauce, covered, and use it as needed. It will keep for weeks.