1Soak chili's in very hot water until soft, about 30 minutes or so. (Make sure they’re submerged by setting a lightweight bowl on top of the chili's.)
In a small skillet, sauté onion in vegetable oil until soft and translucent. Add garlic and sauté another minute. Add spices and herbs and cook, stirring constantly, for about 30 seconds, being careful not to let them burn.
In a blender, peanut butter, cooked onions, tomatoes, spices, raisins or prunes, sesame seeds, salt, pepper, and water. Puree until smooth.
Remove seeds and stems from the chili's andpo (red) puree very finely, passing the chili's through a food mill. (If you don’t have a food mill, press the puree through a mesh strainer to make remove any skins. Some people just puree them in, but they can be tough.) Blend the chili paste into the mole and add additional water, as necessary, until the consistency is smooth and slightly pourable.
Store in the refrigerator until ready to use.