Maybe Charm City Cupcakes in charles st...

http://www.charmcitycupcakes.com/

Looking for some good fish tacos; I have yet to try Tortillaria or Las Palmas, which I've heard are v. good--but are there any sit-down places where you can also get some decent margaritas and share a bowl a chips and guacamole (and that are inexpensive)?

I'm dying for authentic Mexican food...a place that has horchata? Baltimore or the area.