For the Salted Rosemary Syrup (makes about 1/2 cup, enough for 8 drinks)
3tablespoonssugar
1teaspoonMaldon sea salt
1sprigrosemary, cut crosswise into 3 pieces
Instructions
Make the syrup
In a small saucepan, combine the sugar, salt, rosemary, and 3 ounces water and warm over medium heat, stirring until the sugar is dissolved. Remove from the heat and let cool to room temperature, then fine-strain and discard the solids. Store the syrup in an airtight container in the refrigerator for up to 1 week.
Make the drink
Fill a collins glass with ice. Add the syrup and juice, then top with soda water and gently stir. Garnish with a grapefruit slice.