Use a knife and cutting board to cut the watermelon into manageable chunks, approximately 1-inch pieces, ensuring seeds are removed if present.
Place the watermelon chunks into a blender, add a pinch of salt, and pour in the lime juice. Blend on high speed until the mixture is completely smooth, with a vibrant pink color and no visible chunks, about 30-45 seconds.
Pour the blended watermelon mixture into a shallow, freezer-safe dish or container, spreading it out evenly with a spatula.
Place the container in the freezer. Every 30 minutes, use a fork or spoon to scrape and stir the mixture to break up ice crystals, repeating this process 3-4 times for a smooth, sorbet-like texture.
Once the mixture is fully frozen and has a firm but scoopable consistency, serve it in bowls with a spoon. Garnish with lime wedges if desired.