370 Golden Gate Avenue (between Hyde and Larkin)
I like this place; it strikes that balance between asepticness and squalor that is the hallmark of a good Mexican joint. Their regular burrito has a nice heft to it, and they don’t put anything weird or messy in it — rice, beans, meat, and salsa. You can get cilantro and onions if you want. I had mine with grilled chicken and the spicy salsa. The grilled chicken is good, but pretty ordinary. The spicy salsa is nice; it’s got big chunks of jalapeno that put some body behind the heat. The regular burrito is also $4.40, which is pretty reasonable in my book.
UPDATE: Taqueria el Castillito has another location on McAllister between Leavenworth and Jones. It’s a little smaller; I like the Golden Gate one better. But for Tower folks, it might be more convenient.