Place the watermelon cubes into the blender jar. Add the fresh basil leaves on top. Pour in lime juice and sweetener if using. Add the ice cubes around the fruit and herbs.
4 cups watermelon cubes, 10 fresh basil leaves basil leaves, 1 tablespoon lime juice, to taste honey or agave syrup, 1 cup ice cubes
Secure the lid on the blender and pulse a few times to roughly chop the ingredients, then blend on high speed for 30-45 seconds until the mixture is smooth and evenly colored, with visible flecks of basil.
Stop the blender and check the consistency. If the mixture is too thick, add a splash of cold water or more lime juice and blend briefly. The final texture should be icy, smooth, and slightly thick.
Pour the smoothie into glasses. Observe the vibrant pink-red color with flecks of green from basil. The surface should be frosty and chilled to the touch.
Garnish with a small basil leaf or a wedge of lime on the rim. Serve immediately with a straw or a spoon, highlighting the icy, pulpy appearance of the drink.
