Grab a cocktail glass, then mash or muddle your mint leaves and sugar until the mint releases its juices.
Add the lime juice & 2oz. of soju (¼ cup or two shots) to your glass, and stir the mixture together.
Add ice to the top of the glass, then either measure or just pour your sparkling water until the glass is filled, and sip away.
Notes
Skip the Muddling: if you can’t find a muddler or other blunt object, or just don't want the hassle of muddling, you can chop up the mint leaves finely and then stir them well with the sugar and lime juice, before moving to the next step.No Sparkles, No Problem: even if you can’t get your hands on sparkling water, never fear, because you can use top water or any sweet fizzy drink you'd enjoy.Using Flavored Soju: if you decide to use a flavored soju rather than plain soju, note that it will make your drink more sweet & flavorful, but it will also decrease the alcohol content by about a third. You’ll probably want to use no sweetener and a plain sparkling water to make up for the extra sweetness. Pineapple or citrus would be my picks, of all the soju flavors.