Add above ingredients to shaker with ice and shake well. Strain into rocks glass filled with ice, top with soda. Garnish with oregano sprig.
“Infusions can be easy to make at home. For a grapefruit-oregano vodka, add the peel from 1 grapefruit plus uncut segments, and about 3 sprigs of oregano (roughly 3 inches long each) per liter. It would be fine for a 750-milliliter bottle, too. I let it steep for about 2 days, then strain everything out.”
– Julia McElroy of Grand Isle Restaurant