3cupsseedless watermelon cubescut 1 inch in size and frozen solid
Add half of the frozen watermelon cubes to a large food processor. Process until the watermelon breaks down and becomes grainy. Stop the food processor and add half of the yogurt. Process until the mixture becomes smooth and creamy, scraping down the sides of the bowl as necessary. Scoop the sherbet into a separate container and repeat steps with the remaining ingredients.
Serve immediately for a frozen yogurt/soft-serve consistency. For a firmer consistency, freeze for 1 to 2 hours and then scoop. Leftovers may be frozen solid, but the sherbet will be very hard and impossible to scoop straight out of the freezer. Instead, place the container of frozen sherbet in the refrigerator to slowly soften for 3 hours before serving, at which point it should be scoopable.
A small (personal-sized) seedless watermelon will yield around 7 cups of watermelon cubes, enough for at least two batches of this recipe. I try to remove as many small seeds as possible while cutting my watermelon into cubes so that the seeds don't end up in the sherbet.
To freeze the watermelon cubes, place them in a single layer on a rimmed baking sheet and place in the freezer for at least 4 hours but preferably overnight. Make sure there's not excess watermelon juice on the pan or the cubes will freeze into a solid mass. I also prefer freezing the cubes on top of a piece of foil or parchment paper which makes it easier to release them from the pan later.
When making this sherbet, be sure to work quickly or the watermelon will start to thaw and the sherbet may become watery.