Using gloves, peel prickly pears by cutting off about ½ inch from each end. Then slice lengthwise, about ¼ inch through from one end to the other lengthwise, cutting through the thick skin. Carefully remove the entire skin in once piece, by hand. It should come off easily in one piece and leave the fruit in tact.

Blend tunas, 3 cups water, and sugar on medium setting for 60 seconds.

Strain through a fine-mesh sieve into large pitcher. You may need to agitate the mixture to let the juice through, avoid pushing through the pulp to keep juice light in consistency. Discard or compost seeds and pulp.

Stir in remaining 3 cups water.

Chill and serve over ice. Garnish with edible flowers, slices of lime or prickly pears, chia seeds, or rim the glass with chili-lime salt (optional).