Paloma

2 oz. blanco Tequila

1 oz. fresh grapefruit juice

3/4 oz. fresh lime juice

1/2 oz. Agave nectar or simple syrup

2 dashes orange bitters

Splash of sparkling water

Garnish with a half moon grapefruit slice

Combine all the ingredients except the sparkling water into a shaker. Add ice, shake vigorously, and strain into a collins glass. Add fresh ice and top off with sparkling water and garnish.