In a large skillet seat the lamb on all sides. Add the garlic cloves and sauté until light brown. Add the wine and reduce by half. Add the tomato juice and Demi glace, and simmer for 15 minutes. Add the rosemary, thyme, and salt and pepper to taste.
Transfer the contents of the skillet to a casserole dish and bake in a 400ºF oven for 10-15 minutes.
Slice the racks along the bone. Ladle the sauce from the casserole dish over the lamb and serve.