This blender-drink classic is must-have at any summer party. For a strawberry margarita, add 1 cup sliced, frozen fresh strawberries (do not salt rim).
Run a wedge of lime, if using, around rims of two glasses. Invert each glass; dip rim into salt. Set aside. Combine sugar and lime juice in a bowl; stir until dissolved. Pour into a blender. Add tequila, Cointreau, and ice; process until smooth. Divide between two glasses; garnish with lime wedges, if using, and serve.