Step 1

Pull grapes from their stems. Set aside 4 whole grapes. Place rest of grapes in blender with 1/4 ounce lime juice (to prevent browning). Blend to completely purée the grapes. Strain the purée through a fine-mesh strainer, pushing it through with the back of a ladle.

Step 2

Fill a cocktail shaker with ice. Add vodka, grape puree, lime juice, simple syrup, lime wedges, and whole grapes. Shake vigorously and pour contents of shaker into an old-fashioned glass without straining.