If desired to imbibe with flair, take a small plate or bowl and fill it with the salt.
Pour the ingredients through a fine-mesh strainer into a pitcher, pressing the solids to get as much liquid out as you can. (Do it in two batches, depending on the size of the blender.)
Place tequila, orange liqueur, lime juice, and seedless watermelon in a blender and give them a good whirl.
