Prepare Uncle Julio's Mango Passion Purée according to recipe below. Set aside.
Pour 1 tablespoon lime juice into a saucer.
Pour chili powder into a second saucer to cover in a thin layer.
Place a cocktail glass, of choice, upside down on the lemon juice saucer to wet the rim.
Move glass to second saucer and place rim into chili powder to coat. Set glass aside.
Cut jalapeño in 1/2. Scoop out seeds and ribs. Cut a thin sliver, from top to bottom, off of one half. Set aside. Keep remaining jalapeño pieces for additional drinks or other uses.
To an empty cocktail shaker add 1/2 ounce lime juice and cilantro. Muddle lightly.
Add ice.
Pour in tequila and mango passion purée.
Shake vigorously.
Add fresh ice to the prepared cocktail glass.
Double strain margarita from shaker to prepared glass.
Garnish with the jalapeño sliver.
Serve.