How to Make It
In a small bowl, mix the chile powder with the salt and sugar. Moisten the outer rim of two rocks glasses with a lime wedge and dip the rims in the chile salt to coat.
Fill a cocktail shaker with ice. Add the grape juice, tequila, lime juice, triple sec and 4 slices of serrano and shake well. Carefully fill the salt-rimmed glasses with ice. Strain the drink into the glasses, garnish with lime wedges, sliced serranos and grapes and serve.