Makes 2 cocktails in 5 oz. martini glasses

Juice of one sour orange (or more if the orange is not very juicy)
Few generous dashes simple sugar syrup
4 jiggers (6 oz.) aged rum
1 jigger (1 1/2 oz.) Grand Marnier or good quality curaçao
Orange slice or twist, for garnish

If you do not have sugar syrup on hand, just make some ahead of time; boil equal amounts of sugar and water together until sugar dissolves and a light syrup forms. Cool, then refrigerate. Chill cocktail glasses. In cocktail shaker, add ice, then the main ingredients listed. Shake thoroughly to mix and chill. Pour into glasses and garnish with an orange slice or twist.