In an ice-filled cocktail shaker, combine 2 oz. soju, 4 oz. tomato juice, ¼ oz. fresh lime juice, ¼ oz. fresh lemon juice, ¼ oz. soy sauce, ½ oz. kimchi brine, and a few dashes of fish sauce and shake to blend. (Alternatively, use two pint glasses to pour it back and forth to mix.)
If desired, mix equal amounts kosher salt and gochugaru on a small plate. Moisten the rim of the glass with a lime wedge or water, then dip the rim in the gochugaru salt and twist to coat.
Pour the drink into an ice-filled pint glass. Garnish with some kimchi skewered on a toothpick (if using).
