As usual, I'm a fan of Tacos El Gordo. This location is a bit smaller than the Charleston location. Also, the parking is kind of a pain and in a shady shopping center complex. Even so, it's a great spot for Mexican food and they're open late.
There's two lines to order, one for asada and one for the other meats, like adobada. Make sure you get in the right line. If you're unsure, ask the cashier to the right upon entry.
Don't forget to ask for the grilled green onions (cebollitas) and yellow peppers (chile gueritos) with your tacos to have an authentic Tijuana experience.