Step 1

Cut a wedge of lime and run it around the rim of a margarita or low-ball glass. Pour coarse salt onto a plate and dip the rim of the glass in the salt.

Step 2

Fill a cocktail shaker half-full with ice. Add tequila, lime juice, and Swerve to the shaker. Seal and shake well until outside is frosted, 10 to 15 seconds.

Step 3

Add ice to the prepared glass, then strain margarita into it Top with sparkling water and stir. Garnish with a lime wedge.