Jello (gelatine) watermelon slices

Found the recipe here: 1 cup boiling water  1 (3-ounce/ 85g) package strawberry-flavored gelatin (or any red Jello) 1 cup chopped fresh or frozen and thawed strawberries (or any other fruit except for pineapple, apparently a chemical in the pineapple won’t let the jello set properly) 1/2 cup cold water or vodka  5 limes, halved, pulp scooped out and discarded, and rind halves reserved  1 teaspoon black sesame seeds, poppy seeds, or basil seeds. I