I'd like some opinions on favorite places to get authentic mexican tacos. My favorite is El Grullense in Redwood City, but I'd like to find something in San Francisco. By authentic, I mean small corn tortillas grilled and filled with fresh meats such as carne asada, al pastor, cabeza, etc. and topped with onions and cilantro. What I'm not looking for are tacos with beans, rice, or other additions.