ON RIVER WALK

Acenar
http://www.acenar.com
Top notch contemporary Mexican food, exotic drinks and view from their patio. 
146 E. Houston St., 78205
Next to Hotel Valencia
Phone (210) 222-2362

Rio Rio Cantina
http://www.rioriocantina.com
Great Riverwalk location with good party space and solid menu choices.
421 E. Commerce Street
San Antonio, TX 78205
Phone - (210) 226-8462

Zuni Grill
http://www.zunigrill.com/
Good food in a great location. One of the few River Walk locations that serves breakfast.
223 Losoya Street on the Riverwalk
Phone - (210) 227-0864

DOWNTOWN

Aldaco's
http://aldacos.net/
A great lunch spot with top notch margaritas, green enchiladas and chicken dishes as well as good party space for group functions.
100 Hoefgen, 78205 in Sunset Station just north of the Alamodome
Phone - (210) 222-0561

Cascabel's Mexican Patio
http://www.yelp.com/biz/cascabel-mexican-patio-san-antonio
A small, funky Unpretentious place with good inexpensive fare from interior Mexico.
1000 S. St. Mary's Street, 78205 in Southtown 
Phone - (210) 212-6456

El Mirador
http://www.elmiradorrestaurant.com/
Don't miss their Saturday morning tortilla soup.
722 S. Saint Mary's Street, 78205 in King William
Phone - (210) 225-9444

La Gloria
http://www.lagloriaicehouse.com/
Billed as a place to "celebrate the rich and delicious street foods from interior Mexico," La Gloria is the perfect place to enjoy with a group.
100 East Grayson at Pearl (walkable along Museum Reach section of Riverwalk)
Phone - (210) 267-9040

Mi Tierra
http://www.mitierracafe.com
Open 24/7/365. Make sure to arrive early to walk the market and save room for the bakery. A Christmas tradition for a lot of families, just be prepared to wait. The neighboring La Margarita has similar food and ambiance.
218 Produce Row, 78207 in El Mercado.
Phone - (210) 225-1262

Rosario's
http://www.rosariossa.com/
Excellent choice with top-notch salsa and great weekday lunch specials. 
910 S. Alamo St., 78205 in King William
Phone - (210) 223-1806