Step 1

Muddle mint, sugar, and lime in the bottom of a tall, sturdy glass, just until mint is bruised and limes have been mostly juiced. (If you over muddle, you will pulverize the mint, which is not what you want.) If you don't have a muddler, use the end of a heavy wooden spoon instead.

Step 2

Add rum, and muddle a tiny bit more to mix.

Step 3

Fill glass with ice, then top with club soda. Serve with cocktail straws if you have them.