I like a regular burrito as much as anyone, but what I really want from a Mexican restaurant is the kind of sauce that involves large quantities of different dried chiles chopped up and cooked together so as to produce a rich and complicated flavor, not just spicy heat. This is what Diana Kennedy's regional Mexican cookbook is about, for example, yet I've never run into it in a Mexican restaurant in California. Do anyone know what I'm talking about? And it's not mole, which is a different concept and readily available on the west side. Where should I go to get it? Any leads much appreciated.