Start by adding the ice, fresh lime juice, orange juice, simple syrup, and salt into your Ninja blender.

Blend on high until the mixture is smooth and slushy.

Take a quick taste to see if you want more sweetness or tartness. Adjust the simple syrup or lime juice as needed for your perfect balance.

If you desire some fizz, gently stir in the sparkling water.

Chill your serving glasses in the freezer for a few minutes.

Pour the slushie mixture into the chilled glasses.

Garnish each with a lime slice.

Enjoy immediately.