Cranberry Relish with Grapefruit and Mint

Using vegetable peeler, remove peel (pink-yellow outer layer only) from 1 grapefruit in strips. Cut peel into 2-inch-long, 1/8-inch-wide strips (about 1/2 cup). Squeeze 1 cup juice from grapefruits. Stir 1 cup sugar and 1 cup water in medium saucepan over medium heat until sugar dissolves. Add grapefruit peel; bring to boil. Reduce heat; simmer until peel is soft, about 15 minutes. Add 1 cup grapefruit juice and cranberries; bring to boil. Reduce heat and simmer until berries burst, about 10 minutes. Transfer to medium bowl. Stir in mint. Cover; chill until cold. DO AHEAD: Can be made 3 days ahead. Keep chilled.