Heat the oven to 220 degrees Celsius.
Combine the garlic, lemon juice, oil and rosemary and rub over the lamb. Place the racks in the oven on a roasting rack and roast for approx 25 - 30 minutes (medium). Remove it from the oven and set aside to rest.
While the meat is resting, heat the stock and balsamic vinegar in a pan. Add the carrots and cover tightly with a lid to cook for 5 - 6 minutes. Remove the cover and add the butter beans, peas and mint and cook for a further 4 minutes.
Serve 3 racks per person over the bean and carrot mix.
Note : a 150g serving of trim lamb provides 69% recommended daily intake of B12, 41% iron and 39% zinc.