Combine all ingredients except jalapeño in a cocktail shaker; mix well.
(Optional) For a salted rim, add salt into a shallow dish. Run a lime wedge around the rim of the glass and twist rim into salt until desired amount sticks to glass.
Add ice to glass and add margarita mix. Garnish with jalapeño slice.
Nutrition Facts
145 calories, 0g fat, 4g carbohydrates, 0g protein