Blend the cubed and deseeded watermelon until completely smooth, about 30 seconds. This creates a juice-based mixture that will give your ice cream its signature flavor and natural sweetness. Strain through a fine-mesh sieve if you prefer an ultra-smooth texture, though this step is optional.

Pour the heavy cream into a large bowl and beat with an electric mixer on medium-high speed for about 6 minutes until soft peaks form. This incorporates air into the cream, which creates the light, creamy texture that defines great ice cream. Don't overbeat or you'll end up with butter, so watch carefully as you approach the 6-minute mark.

In a separate bowl, whisk together the watermelon juice from Step 1, condensed milk, lime juice, salt, and vanilla extract until well combined. The lime juice brightens the watermelon flavor and prevents the ice cream from tasting overly sweet—I find this acid balance is crucial for a truly refreshing result. The salt enhances all the flavors while the vanilla adds subtle depth.

Gently fold the watermelon-condensed milk mixture from Step 3 into the whipped cream from Step 2 using a rubber spatula, folding until just combined and no white streaks remain. Be gentle to preserve the air you've whipped into the cream—this is what makes the ice cream creamy rather than icy. Transfer to a freezer-safe container and freeze for at least 6 hours, or until firm. I like to scoop out a small taste after 4 hours to check the texture, then cover it back up to finish freezing.