Sparkling Grapefruit Cocktail

Preparation

1. Step 1

   Remove zest, along with some of the white pith, from grapefruit in wide strips with a vegetable peeler. Bring sugar and ¼ cup water to a boil in a small saucepan, swirling constantly, until sugar dissolves. Remove from heat and add grapefruit zest, pushing down to submerge. Let sit 30 minutes, then strain through a fine-mesh sieve into a measuring cup.

   Step 2

   Combine gin, lemon juice, tarragon, and ½ ounce syrup in a cocktail shaker. Fill shaker with ice, cover, and shake vigorously until outside of shaker is very cold, about 20 seconds.

   Step 3

   Strain cocktail into an old-fashioned or rocks glass filled with ice. Top with sparkling wine and garnish with grapefruit wedge.

   Step 4

   Do Ahead: Syrup can be made 1 week ahead; cover and chill.