In a collins glass or highball glass, add the mint leaves and simple syrup.
Muddle to release the oils of the mint leaves. (See note for an alternate method.)
Top with ice cubes, filling the glass all the way.
Add the lemon juice and rum. Top with club soda. Stir gently.
Garnish with a straw, lime wedge and a mint sprig.
Notes
No muddler? Use the blunt end of a wooden spoon.If you don’t like chunks of fruit in your cocktail, make the drink in a shaker or mixing glass (except the club soda) then strain into your drinking glass and top with club soda.For a lemon-lime variation: Use ½ ounce each of lemon juice and lime juice.Want to make a big pitcher? Use the +/- buttons at the top of this recipe card to scale the recipe as you need to.To make simple syrup: In a medium saucepan over medium heat, combine sugar and water. Stir until sugar has dissolved. Remove from heat. Let cool completely before using. (Add a few ice cubes if you need it ASAP.) Transfer to a glass jar and seal tightly with a lid. Store in the refrigerator for up to 1 month.