Serving Size: 6
Arrange racks in large pot, add water to cover. Cover pot and cook over low heat for 1-1/2 hours. Drain and pat dry and set aside.
In small bowl, whisk together ½ cup vinegar and olive oil; brush racks on all sides. Season racks with salt and rub all over with garlic and rosemary. Cover tightly, and allow to stand in refrigerator at least 6 hours.
Arrange lamb on rack in shallow roasting pan. Cook at 325 degrees F. for about 1-1/2 hours. Meanwhile, combine remaining balsamic vinegar with honey; mix well and set aside. After about 1-1/2 hours, brush the balsamic honey mixture all over ribs and continue to cook for 20 minutes longer, basting frequently. Transfer ribs to cutting board; cut between bones and serve.
To grill: arrange racks on hot grill and cook 30 to 35 minutes, turning occasionally. Brush generously onto all sides of racks and continue grilling until sauce forms sticking coating, about 4 minutes per side. Transfer to a cutting board, cut racks between bones and serve.