Coarse salt, optional
1 Tbs. lime juice
1 1/2 Tbs. orange juice
1 tsp. agave nectar
Splash of soda water
Salt rim of glass, if desired, by dipping it in a bowl of water and then in salt.
Pour juices and agave into an ice-filled shaker. Shake, then pour drink and ice into prepared glass and top with soda water.