Step 1: Wash the watermelon thoroughly. Cut it into large wedges, remove the rind, and chop the pink flesh into roughly 1-inch cubes. You should aim for about 8 cups of cubed watermelon.
Step 2: Place the watermelon cubes, fresh lime juice (if using), and 1 tablespoon of your chosen sweetener (if using) into a high-speed blender. Blend until the mixture is completely smooth and liquid, ensuring there are no lumps.
Step 3: For the smoothest texture, strain the blended watermelon mixture through a fine-mesh sieve set over a large bowl. Press down on the solids with a spoon or spatula to extract as much liquid as possible. Discard any pulp or seeds remaining in the sieve.
Step 4: Taste the strained watermelon liquid. If your watermelon isn’t very sweet or you prefer a sweeter sorbet, add additional sweetener (1 tablespoon at a time) and blend or whisk until fully dissolved. Remember that frozen desserts taste less sweet, so it’s okay for it to be slightly sweeter at this stage.
Step 5: Cover the bowl and chill the watermelon mixture in the refrigerator for at least 1-2 hours, or preferably overnight. This step is crucial for achieving a creamy texture and preventing large ice crystals.
Step 6: If using an ice cream maker, pour the chilled mixture into your ice cream maker’s frozen bowl and churn according to the manufacturer’s instructions (usually 20-30 minutes) until it reaches the consistency of soft-serve ice cream. If making no-churn, pour the chilled mixture into a shallow, freezer-safe dish or pan. Place in the freezer. After 45-60 minutes, remove and use a fork to vigorously scrape and break up any ice crystals. Repeat this scraping process every 30-45 minutes for a total of 3-4 hours, or until firm but scoopable.
Step 7: Transfer the churned or scraped sorbet into an airtight freezer-safe container. Freeze for an additional 2-3 hours to allow it to harden to a scoopable consistency. When ready to serve, let it sit at room temperature for 5-10 minutes to soften slightly for easier scooping. Enjoy your refreshing homemade watermelon sorbet!