Calamansi Rickey Cocktail

To prepare syrup: Bring calamansi juice (or lemon juice and orange juice), sugar and water to a simmer in a small saucepan over medium-low heat. Cook, stirring once or twice, for 5 minutes. Remove from heat and let cool. Transfer to a lidded jar and refrigerate until chilled, about 30 minutes and up to 1 week.

To prepare cocktail: Fill a low-ball glass with ice. Add 2 ounces calamansi syrup, club soda and gin; stir. Garnish with candied lime or lemon, if desired.