To serve: sparkling water, coarse sea salt, lime slices and fresh mint
BLEND: Fill your blender with watermelon chunks about 3/4 full beneath the max fill line, then add the ginger (no need to peel), lime juice and fresh mint. Blend until you have a watermelon juice with no visible bits.
STRAIN: Place a fine mesh strainer over a large pitcher and pour the watermelon juice through to strain out the pulp a little at a time. Use a spoon to stir up and press down on the pulp each time, then remove and discard it. Repeat until all of the juice has been strained. Add the remaining watermelon to the blender and juice it. Repeat the blending and straining process until all of the watermelon is juiced and pulp free.
CHILL: Refrigerate the watermelon juice until well chilled, at least three hours.
SERVE: I like to salt the rim of the glasses when serving this Watermelon Agua Fresca. Pour plenty of coarse sea salt onto a small shallow plate. Rub each glass with a wedge of lime, then invert the glass and dip in the salt to coat. Repeat until all the glasses are salted. Serve the Watermelon Agua Fresca over ice with a slice of lime and sprig of mint, filling each glass about two thirds full and topping them off with sparkling water. Use crushed ice for a slushy like texture, or add a splash of your favorite adult beverage. I won’t tell!