This favorite from Square 1682 in Philadelphia is made with fresh lime juice, good-quality tequila, and agave nectar or syrup. (It's easy to make a big batch ahead of time to serve a crowd; just combine all ingredients except the ice together in a pitcher.) — Allison Beck
Rim lowball glass with sugar or salt. Fill glass with ice. Mix ingredients together and pour over ice. Garnish with a wedge of lime.