If you haven’t already frozen your fruit, ensure it’s nice and ripe and juicy (the sweeter, the better) then slice and freeze on a parchment-lined baking sheet. Freeze overnight or for at least 4-6 hours or until firm like ice. (Note: Prep time does not include this step.)
To a high-speed blender (or food processor) add frozen watermelon, frozen strawberries, and frozen banana. Top with the lesser amount of dairy-free milk of choice or coconut water.
Blend on low, then on high, using the tamper to blend the ingredients together if using a high-speed blender. If using a food processor, blend in 30-second increments, then remove lid and scrape down sides as needed.
If it has trouble blending, add more dairy-free milk or coconut water a little at a time. Be sure not to add too much or the sorbet can get too liquidy. Alternatively, you can try letting the fruit thaw slightly in the blender before resuming. Taste and adjust flavor as needed. Add more fruit of choice if you want more of its flavor to come through (we go heavy on watermelon and it doesn’t disappoint).
Transfer to a serving bowl and enjoy immediately (recommended!), plain or topped with sliced fruit of choice. Or, transfer to a parchment-lined loaf pan, cover with more parchment paper, and freeze until firm, then scoop and serve in a bowl or on a cone.
Leftovers will keep in the freezer up to 2 weeks. If not freezing in a loaf pan, this sorbet freezes well in popsicles or ice cube molds (blend again later with more dairy-free milk or coconut water to achieve sorbet consistency).