In a cocktail shaker, combine tequila, triple sec, passion fruit juice, lime juice, and agave syrup.
Add a handful of ice cubes.
Shake vigorously for about 15-20 seconds.
Strain the margarita mixture from the shaker into a glass filled with ice.
Garnish with a lime wedge or a slice of fresh passion fruit.
If desired, rim the glass: Take a lime wedge and rub it around the rim of a margarita glass. Dip the rim into a plate of salt or sugar, rotating it to coat the rim evenly.