Crush together the sea salt flakes and lime zest in a small bowl. Rim a margarita glass by rubbing a lime wedge around the edge of the glass and then dipping it in the lime salt.
Muddle the jalapeno and ginger with a few ice cubes in a cocktail shaker. Then add the tequila, lime juice, orange liqueur and Simple Syrup. Shake and strain into the margarita glass filled with ice.
Heat the sugar and 1 cup water in a small saucepan. Simmer until the sugar is dissolved. Let cool. The syrup will keep in the refrigerator for up to 2 weeks.