Cut the watermelon into 1-inch cubes and place them in your blender. I like to chill the blender bowl in the freezer for 5 minutes before blending—this keeps the shake colder longer and prevents the ice cream from melting too quickly during blending. While the blender chills, measure out the vanilla ice cream, salt, lime juice, and tear the mint leaves by hand to release their oils.

Add the watermelon cubes to your blender and blend on medium speed for 30 seconds until you have a smooth puree. This initial blending breaks down the watermelon and releases its juice, creating a foundation for a silky shake.

Add the vanilla ice cream, salt, and lime juice to the watermelon puree from Step 2. The salt and lime juice may seem like small additions, but they're crucial—the salt intensifies the watermelon flavor and balances the sweetness, while the lime juice adds brightness and prevents the shake from tasting flat.

Blend on medium speed for another 30 seconds until all ingredients are fully combined and the shake reaches a smooth, creamy consistency. Add the torn mint leaves from Step 1 and pulse 2-3 times just until they're flecked throughout the shake—don't over-blend or the mint will become bitter. Pour immediately into chilled glasses and serve right away for the best texture.