Pour the lemon-lime soda into a freezer-safe container and sprinkle the salt evenly over the surface. Give it a gentle stir to combine—this helps the salt dissolve slightly and distributes flavor throughout once frozen.
Place the container in the freezer and let the mixture freeze solid for about 2 hours. Check occasionally to ensure it’s not overfreezing.
Once frozen, remove the container from the freezer using a towel or oven mitts. Use a fork or spoon to scrape and stir the icy mixture, breaking up any large chunks and creating a fluffy, slushy texture.
Continue to stir every few minutes until the mixture reaches a finely crushed, icy consistency that’s easy to scoop and looks frosty and opaque.
Serve the slushie immediately in glasses or bowls, garnished with a twist of citrus if desired. The final result should be a bubbly, crunchy, salty-sweet frozen treat.
