Blend ½ cup grapefruit juice, 2 Tbsp. lime juice, 2 Tbsp. fresh ginger (peeled and chopped), and a dash of salt. Divide the mixture between two glasses (because, why drink alone?) filled with ice. Top with seltzer and stir. Garnish with rosemary sprigs, swirling in the glass to infuse flavor. Cheers to Diana Licalzi Maldonado, R.D.N., L.D.N., author of Drinking for Two: Nutritious Mocktails for the Mom-to-Be, for the recipe.