Pour 6 oz light rum, 1 oz fresh lime juice and 1/2 oz simple syrup into a cocktail shaker or large mixing glass. Add the ice (use the 6 cubes) and cap the shaker.

Shake / Mix

Shake vigorously for 10–12 seconds if using a shaker. If using a mixing glass, stir well for 15 seconds with a bar spoon until well chilled and slightly diluted.

Divide

Strain the chilled rum-lime mixture evenly into six highball glasses (about 1 oz rum mixture per glass). If using a pitcher, pour the entire mixture into the pitcher and then divide among glasses.

Top with ginger beer

Top each glass with 2 oz (about 1/4 cup) chilled ginger beer, adding up to a total of 12 oz ginger beer. Leave a small gap at the top for garnish. If you prefer more fizz, top with up to 3 oz per glass.

Finish and garnish

Add one dash of Angostura bitters to each glass (total 3 dashes). Optionally add crushed ice to each glass if using. Garnish each drink with a mint sprig and a lime wheel. Serve immediately.

Notes

This recipe yields six small highball-style cocktails (a '6-Pack'). Adjust rum and ginger beer proportions to taste. For a non-alcoholic version, replace rum with extra ginger beer and 1 oz soda water per serving.