Puree watermelon in blender (makes approx 6 cups)
Pour two cups into 2 standard size ice cube trays; freeze until solid and reserve remaining 2 cups in fridge.
When you are ready to enjoy, place 1 tray of the frozen fruit, 1 cup soda, 6 TBSP lime juice and 1 TBSP rum extract into the blender and blend until smooth, stir in 1 1/2 TBSP of the mint leaves and pour into glasses. You can garnish with additional mint leaves if desired. Makes 4 - approx. 1 cup servings