1.Place beans in medium bowl, cover with cold water; stand overnight, drain. Rinse under cold water; drain. Cook beans in medium saucepan of boiling water, uncovered, about 15 minutes or until beans are just tender; drain.
2.Preheat oven to 160°C (325°F).
3.Combine garlic, chopped rosemary, salt, pepper and 1 tablespoon of the oil in small bowl. Place lamb, cut-side up, on board; rub garlic mixture into lamb. Roll lamb tightly; secure at 2cm (¾ inch) intervals with kitchen string.
4.Heat remaining oil in large deep flame-proof baking dish on stove top; cook lamb until browned all over. Remove lamb from dish.
5.Cook onion, carrot and celery in same heated dish, stirring, until onion softens. Add beans, bay leaves, rosemary sprigs, wine and stock to dish; bring to the boil.
6.Return lamb to dish, cover; transfer to oven, cook 1 hour.
7.Uncover; cook in oven 30 minutes. Discard herbs; remove lamb from dish. Cover lamb; stand 10 minutes, then slice thickly.
8.To make mashed potatoes, boil, steam or microwave potatoes until tender; drain. Mash potato with butter and cream until smooth.
9.Serve lamb on vegetable mixture, accompanied with mashed potatoes.
Braising is a cooking technique that is usually used for tougher, less expensive cuts of meat. The meat is seared, or browned, and then simmered in liquid on a low heat in a covered pot. The resulting meat is beautifully tender and flavourful. Slow cooker: suitable to the end of step 6. Pressure cooker: suitable to the end of step 6. Suitable to freeze at the end of step 7.