How to Make It
Cut the peel from the grapefruit in large strips, including about 1/4 inch of the white pith. Reserve the grapefruit. Put the peels in a medium saucepan and cover with cold water. Bring to a boil over moderately high heat, drain and repeat 3 more times. Cut the blanched peels into 1/4-inch dice; reserve.
Meanwhile, juice the grapefruit. In a large saucepan, combine the grapefruit juice, cranberries, 1 1/4 cups plus 2 tablespoons of the sugar and 1 1/2 cups of water and bring to a boil. Simmer over low heat, stirring occasionally, until the liquid has reduced by half and the cranberries are cooked down, about 1 1/2 hours.
In a medium saucepan, combine the reserved grapefruit peel with the remaining 1 cup plus 2 tablespoons of sugar and 1 cup of water and bring to a boil. Simmer over moderate heat, stirring occasionally, until the peel is translucent, about 40 minutes. Add the peel and syrup to the cranberry mixture and simmer over moderate heat, stirring occasionally, until reduced to 3 cups, about 25 minutes. Serve at room temperature or slightly chilled.