1/2 oz Bitter Apéritif (I recommend Campari or Aperol)
1/2 oz Simple Syrup
2-3 Dashes of Aromatic Bitters
2 oz Soda Water
Combine all ingredients, except for the soda water, into a cocktail shaker and shake with ice. Strain the drink into a rocks glass over ice, and top with soda water. Garnish with a grapefruit wedge and lime wheel.