Put 2 tsp. ginger, 1/2 tsp. bitters, and 1 tsp. juice into each of 2 tall cocktail glasses. Fill both glasses with ice. Add rum (if using), dividing evenly, and top each glass with ginger beer.
Note: Nutritional analysis is per serving.
Servings 0
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.