• 1 Lamb shoulder
• 5 cloves of garlic, peeled and halved
• 2 large red onions, peeled and thickly sliced
• 100g butter
• 1 tablespoon dried oregano
• 100ml balsamic vinegar
• 1 tablespoon horseradish
• 1-2 teaspoons salt
• 800g canned chopped tomato
• 200ml tomato juice or water
• 1kg sweet potatoes, orange or white fleshed, peeled
• 2 tablespoons rosemary leaves, chopped
• 50ml extra virgin olive oil
• 150ml double cream
• 100ml water

Set oven at 180°C. Poke a thin sharp knife into the lamb in 10 places and insert half a clove of garlic in each slit. Heat up a pan and sauté the onions in the butter until caramelized, then mix in the oregano and vinegar and simmer for one minute. Stir in the horseradish, 2 teaspoons of salt, the tomatoes and 400ml water or tomato juice and bring to the boil. Put half of the tomato mixture into a 10cm deep roasting dish, sit the lamb on top, then pour on the remaining tomato mixture. Seal the dish tightly with foil, or place a tight fitting lid on and bake in the oven for 30 minutes. Cut the sweet potatoes into 1cm thick slices. Toss with a little salt and pepper and the rosemary. Brush a 15cm square roasting dish with the olive oil and place the potatoes in layers, pouring over the cream and water. Cover tightly with foil and bake in the oven with the lamb for 40 minutes. Take the foil off both the lamb and the gratin. They should take about another 10-15 minutes each, so keep them cooking to color slightly.

To Serve:

To serve, spoon some gratin on a plate then slice the lamb and lay on top. Spoon over the tomato sauce.