Ingredients

• 1 small red beet (1/4 pound), scrubbed
• 1 (6-pound) ripe cantaloupe, peeled, seeded, and chopped (12 cups)
• 4 cups cold water, divided
• 1/4 cup fresh lime juice
• 1/4 to 1/3 cup plus 1 tablespoon sugar, divided

Instructions

1. Preheat oven to 425°F with rack in middle.
2. Wrap beet in foil and put in a small 4-sided sheet pan, then roast until tender when pierced with a knife, 45 to 50 minutes. Unwrap and let stand until cool enough to handle.
3. While beet roasts, purée cantaloupe, 3 cups water, lime juice, and 1/4 to 1/3 cup sugar (to taste) in 3 to 4 batches in a blender until very smooth, about 1 minute per batch. Chill agua fresca until cold, about 2 hours.
4. Peel and chop beet, then purée with remaining cup water and remaining tablespoon sugar in cleaned blender until smooth. Chill beet purée until cold, about 2 hours.
5. To serve, pour agua fresca over ice in tall glasses, then dollop 1 Tbsp beet purée on top of each drink, swirling it decoratively with a spoon.