Ingredients: 1 oblong seedless watermelon (about 14 pounds) 3 cups seltzer Directions: Cut top third off watermelon; trim bottom just enough to make a flat surface. Scoop out flesh. Working in batches, puree watermelon in a food processor. Strain through a fine sieve; discard solids. (You should have about 9 cups juice.) Cover rind with plastic wrap. Refrigerate juice and rind until chilled, about 1 hour. Combine juice with seltzer; transfer to rind.