Combine rhubarb, sugar, water, orange liqueur or thawed frozen orange juice concentrate, and orange peel in a medium saucepan. Bring to boiling; reduce heat. Cover and simmer about 5 minutes or until rhubarb is tender. Remove from heat; let cool.
Place turkey on a rack in a shallow roasting pan. Spread 1/4 cup sauce over turkey. Roast in a 375 degree F oven for 40 minutes. Spread 1/4 cup more sauce over turkey. Insert a meat thermometer into the thickest portion of turkey breast, without touching bone. Continue roasting about 35 minutes more or until thermometer registers 165 degrees F. Let turkey stand, covered, for 10 minutes before slicing. Meanwhile, reheat remaining sauce and serve with turkey. Makes 6 to 8 servings.