1. Cover the shoulder of lamb liberally with salt. Cover and leave overnight (for around 12 hours), then, under a cold tap, wash off the excess salt. Pat the lamb dry with a kitchen cloth or tea towel.
2. Preheat the oven to 140°C/Gas Mark 1.
3. On both sides of the shoulder make small cuts and stuff with the rosemary and garlic. Put the shoulder in a deep roasting tin and cover with the duck fat, place baking paper and foil on top of the tray to cover. Slow cook for 3 to 3 1/2 hours.
4. When cooked remove from the oven and leave to cool for a few minutes. Then take the lamb out of the pan and place it on to a tray to cool completely and set. Cut the lamb into 10 pieces with a very sharp knife on a carving board then leave to one side.
5. To make the gravy, sweat the shallots in oil until they begin to brown, then pour in the Madeira and reduce by three-quarters. Add the chicken and lamb stock and continue to reduce until it has suitably thickened. Finely sift then stir in the butter and set aside.
6. To make the purée, add the potatoes in a pan of salted water and simmer until thoroughly cooked. Drain the water, then mash with the milk, butter and salt, until all the lumps are removed. Place the mash into a piping bag and keep warm.
7. Poach the tomatoes in the white wine and olive oil with the garlic and rosemary on a low heat. Season with salt and pepper.
8. Place the beans in a saucepan filled with salted water at the boil. Cook for 3-4 minutes. Plunge into iced water. When the beans are cold, drain and leave a small tray until needed.
9. When ready to serve, preheat the oven to 200°C/Gas Mark 6. Heat the lamb portions through in the oven until hot in the middle and crispy on the outside.
10. Warm the piping bag of mash, reheat the gravy in a small pan and reheat the beans in a small amount of butter. Season with salt and pepper.
11. Pipe the mash onto each plate, add a portion of shoulder, some of the green beans and a poached tomato. Drizzle a little of the gravy onto the lamb, and serve any extra on the side.
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