How to Make It
1. Peel three of the limes by lopping off the tops and the bottoms of each one, cutting just deep enough to expose the fruit beneath the pith. Stand each lime on your cutting board—it should be nice and steady. Cut the remaining peel and pith off the lime in wide strips, working your way around the fruit, so that you end up with a complete, peeled piece of fruit. Discard the peels or reserve them from another use. (Julia likes to simmer them with water and brown sugar, then strain the liquid and serve it over ice. She notes that a little tequila wouldn't hurt one bit.) Cut the remaining lime into thin slices.
2. Put the peeled limes in a blender; add the honey or agave, juice (or 3 cups of the strawberries or blueberries), tequila, and salt; and blend until combined. Add the ice (see notes above—you likely will need to do this in batches) and let the machine run until the ice is totally blitzed and the mixture is very smooth.
3. Pour into four glasses and garnish with the lime slices. Serve immediately.
Adapted from the recipe for Paloma Slushies in Julia Turshen's Small Victories: Recipes, Advice + Hundreds of Ideas for Home Cooking Triumphs