Firefighter's Sour

Juice 2 fresh limes and set the juice aside, discarding any seeds.

Fill a cocktail shaker with ice, then add the rum, fresh lime juice, and a teaspoon of powdered sugar.

Secure the lid on the shaker and shake vigorously until the outside of the shaker feels cold, about 15 seconds.

Fill a tall glass with fresh ice and strain the shaken mixture over the ice.

Top the drink with a splash of club soda, gently stirring once to incorporate without losing carbonation.

Slowly pour grenadine over the back of a spoon held just above the surface of the drink so it sinks and creates a vivid crimson float at the bottom.

Garnish with a lime wheel or cherry if desired, and serve immediately.