Add a handful of ice cubes, tequila, and triple sec to your cocktail shaker.
Add the fresh lime juice.
Add the mango juice, slices of jalapeno, and agave, if desired. Shake until the mixture is combined and chilled.
To rim your margarita, run a lime wedge around the rim of your glass, then dip the glass edge into the Tajin seasoning.
Pour the drink into your margarita glass, then garnish with a lime wedge or a slice of mango.
Notes
Mango juice, also called mango nectar, can usually be found in the Mexican food section of your grocery store. If you can’t find it, you can also make this cocktail with pineapple juice.