I really like Brasas (on 1st south and Freedom) for a couple of authentic carne asada tacos or an excellent fish taco. It's a shack, and inexpensive, but really good.

I like Spicy Thai for their lunch special. Get the Tom Kha Gai soup, the chicken satay, and whatever curry they offer, and it's a solid lunch for not much money.

La Dolce Vita will cost a little more, but not that much, and it's a really excellent authentic Italian. They have some lunch specials too, and everything on the lunch menu is good (I love the Chicken Parmesan).

El Mexsal is decent Mexican food. Not a great ambiance, but not horrible either. Their pupusas are really good. I like their chile relleno too.

Sam Hawk is excellent Korean. I love their bulgogi.

Those are some of my favorites.