Pour a mound of salt onto a small plate and spread out slightly. Rub a lime wedge around the rims of two rocks or margarita glasses. Dip rims of glasses into salt and turn to coat. Fill glasses with ice.
In a cocktail shaker, combine the Seedlip, pineapple, lime juice, cilantro, and agave, if using. Using a muddler or the back of a thick wooden spoon, mash mixture until the pineapple and cilantro are well broken up.
Fill the shaker with ice, cover, and shake vigorously until very cold. Strain into the prepared glasses and garnish with pineapple, pineapple leaves, and lime rounds. Serve immediately.