Place guajillo peppers and plums in large heatproof bowl. Add 1/2 cup boiling water. Let stand 10 to 15 minutes to allow peppers and plums to hydrate.
Place water with peppers and plums, brown sugar, vinegar, salt, pepper, spices and remaining 1 cup water in blender container; cover. Blend on high speed until completely smooth.
Press chile pepper mixture through a sieve to remove skins. Stir in peanuts and crushed red pepper. Serve as a dip with plantain chips or as a salsa for topping various Mexican dishes.
Test Kitchen Tips:
•This sauce can be made using a variety of dried chiles including guajillo, ancho, pasilla or morita, depending on your desired heat and flavor level.
•The Guajillo chile is the dried form of the mirasol chile and is one of the most frequently used dried chiles in Mexican cuisine. Used in marinades, salsas, pastes and spice rubs, the guajillo has mild to medium heat and a smoky, slightly sweet and fruity flavor.
•The Pasilla chile is the dried form of the chilaca pepper. Pasilla chiles bring rich, smoky flavor and mild to medium heat to Mexican dishes.
•This is not a traditional Mexican sauce, but it does use traditional Mexican ingredients for a sweet-sour, smoky flavor.