If the loins are very large cut them lengthwise to about 6 oz. each for ease of cooking and portioning. Rub lamb all over with black pepper and red pepper flakes, and oregano leaves. Cover with plastic wrap and refrigerate for several hours, or overnight. Mix the balsamic vinegar and brown sugar well to dissolve it. Set aside. Heat the olive oil in a small sauté pan. Add the garlic, and, stirring often, lightly brown it. Be sure it is done and very soft. Remove pan from heat and let cool a few minutes. Mash the garlic to a smooth puree with a fork. Carefully pour the mixture into the pan with the pureed garlic and simmer until it is reduced by about half and becomes the consistency of syrup, about 10 minutes. Set aside (can be made a day or two ahead). Bring the lamb to room temperature. Pre-heat oven to 375 degrees and place lamb loins in a small roasting pan leaving space among them. Roast for about 12 to 14 minutes for medium rare. Remove from oven and while still hot baste with the balsamic mixture using a brush; let rest for 10 minutes, baste again. Carve and serve.
Ready in 50 min