It’s the high season for cool, slushy drinks. Nina Planck, author of several Real Food cookbooks, says her fermented watermelon basil cooler illustrates one of her key principles: when she processes food, she does it in ways that enhance nutrition, flavor, and shelf life.  Nina Planck / photo by  Katherine Wolkoff Nina's recipe for fermented watermelon basil cooler (Makes two quarts) Ingredients 8–10 lb watermelon 8–10 Meyer lemons small bunch of Genovese basil 1/4 c organic whole cane sugar 1/4 c fresh whey 1 T unrefined sea salt 3 c water Make 3 cups of watermelon juice in a blender or food processor. Don’t strain the pulp. Squeeze 1 cup of lemon juice. Take 1/2 cup of basil leaves and gently bruise them using a mortar and pestle to release the oil. Put all the ingredients in a 2-quart glass jar, cover with water, and close the lid tightly. Stir and leave out at room temperature for 3 days. Allow a little carbonation to escape when necessary and replace the cap firmly. Chill and serve. Keeps up to 2 weeks in the fridge.