Once the nectar of frat parties, Mexico's favorite liquor has come of age. T+L talks to San Francisco-based tequila expert and restaurateur Julio Bermejo about how to drink it like a pro. GET REAL Look for 100 percent agave, the tuberous plant from which the spirit is made. KNOW YOUR AGE Blanco is unaged, herbaceous, and clear. Reposado, aged up to a year, is fuller bodied, and añejo, one to three years old, has an oaky flavor and deep tan hue. SKIP THE MARGARITA Sip it like they do south of the border. ORDER IT COMPLETO You'll get tequila and a palate-cleansing sangrita made of tomato, orange, and lime juices. THREE FOR THE ROAD Try the ceviche and a reposado at OYAMEL (2250 B Crystal Dr.; 703/413-2288; dinner for two $60) in Arlington, Virginia. London's MESTIZO (103 Hampstead Rd.; 44-207/387-4064; dinner for two $62) is the sexiest tequila bar in Europe. In San Francisco, Bermejo's TRES AGAVES (130 Townsend St.; 415/227-0500; dinner for two $50) has 100 varieties. ¡Salud! —CLARK MITCHELL

Tres Agaves

Enjoy blue-agave tequilas and Mexican cuisine at Tres on Townsend Street in the SoMa District. Its brick façade features a trio of agave plants above the arched doorway. Inside is a rustic-industrial-Mexican blend of brick walls, an exposed ceiling, a massive wall mural, and a cage-like divider filled with smooth gray and white rocks. Executive chef Kelvin Ott focuses on fresh Bay Area ingredients and fresh-pressed corn tortillas to prepare Jaliscan dishes cooked in mesquite ovens, like al pastor pollo (seasoned chicken) taco platter and carne en su jugo ("meat in its juices"). The bar serves lime margaritas, tequila cocktails, and Mexican beers.

El Burrito by Mestizo

Just outside St. James Gardens, El Burrito serves crowd-pleasing burritos, tacos, quesadillas, and nachos to be washed down with fresh jugos or ice-cold Pacifico beer. The restaurant does a bustling trade and is designed for takeout or quick meals in the green-and-white, cafe-like space, which features a bar and fast-food-style banquettes. Tacos al pastor with marinated pork and pineapple and choriqueso alambres, which combines grilled chorizo, bacon, peppers, onion, and melted cheese in a corn or flour tortilla, are typical fare in this casual establishment.