In a pitcher or large mixing glass, combine the freshly squeezed lime juice and agave syrup or honey. Stir until the sweetener is fully dissolved.
Add the sparkling water to the pitcher and stir gently to combine. Taste the mocktail and adjust the sweetness or tartness as desired by adding more agave syrup or lime juice.
Fill serving glasses with ice cubes and pour the mocktail over the ice.
If desired, rim the glasses with salt by running a lime wedge around the rim and dipping it in salt.
Garnish each glass with a lime wedge and serve immediately.
Notes
For an extra burst of flavor, try adding a splash of orange juice or a dash of orange bitters to the mocktail.
To make a frozen margarita, blend the ingredients with ice until smooth and slushy. Adjust the consistency by adding more ice or liquid as needed.