Margarita Mocktail

Bahan-bahan (1 porsi)

• 1 1/2 ounces (3 tablespoons) freshly-squeezed lime juice
• 1 ounce (2 tablespoons) freshly-squeezed orange juice
• 1 to 2 teaspoons agave nectar
• 1/3 cup sparkling water (or club soda)
• coarse sea salt (or margarita salt), for rimming
• extra lime slice, for garnish