Step 1

Combine the lime juice, orange juice and agave in a spouted measuring cup. Pour into a 12-compartment ice cube tray and freeze until solid, at least 4 hours and up to overnight.

Step 2

Pour the salt into a small dish. Dip the rims of 2 glasses in water, then dip the rims in the salt to coat.

Step 3

Combine the ice cubes, seltzer and frozen juice cubes in a blender and blend on high until smooth and pourable. Pour into the prepared glasses and serve immediately.