Preheat the oven to 200 °C / 400 °F / Gas Mark 6. Heat half the oil in a flameproof casserole dish and cook the onions and carrots for about 10 minutes. Remove with a slotted spoon.
Season the meat with black pepper, add to the pan in batches, and fry on all sides for 2-3 minutes over a hot flame.
Mix together the orange zest and juice, tomato puree, vinegar, sugar, mustard and 400ml water.
Pour this over the meat. Cover and cook in the preheated oven for about 30 minutes.
Take the meat out of the oven and add the sultanas or raisins and plums. Continue to cook for a further 45 minutes or until the plums have collapsed and the meat is piping hot.