2-3 jalapeño slices (remove seeds to make less spicy)
1.5 oz grapefruit juice
pinch kosher salt
pinch chile powder
Rub a lime around the rim of a rocks glass, then dip in a mixture of equal parts chile powder and kosher salt. Muddle jalapeños with margarita mix in a shaker tin. Add remaining ingredients and ice and shake. Strain into prepared rocks glass over ice. Garnish with grapefruit wedge and jalapeño slice.