Place everything into a cocktail shaker filled with ice.
Shake it up!
Strain into a salt-rimmed glass filled with ice.
How to Make Watermelon Juice:
Place 3-4 cups of diced watermelon in a blender and purée until smooth.
Strain the pureed watermelon through a fine mesh sieve, reserving the juice.
Repeat until you have all the watermelon juice you want!
Chill until ready to use.