To rim the glasses, gently moisten the rim of four glasses with a lime wedge. Pour about 1/4 cup of salt on a plate then gently move the moistened rim around to coat with the salt. Fill each glass with ice then set aside.
In a cocktail shake, mix together tequila, lime juice and orange juice with ice. Shake well then pour mixture over four glasses, about 2/3 full. Top each glass with sparkling water to serve.
This recipe is not meant to be sweet but if you prefer a sweeter margarita, replace orange juice with orange liqueur and add in simple syrup to taste.