Preheat the oven to 200C/180C fan/gas mark 6. Heat the oil in a casserole over a medium-high heat. Season the meat well and brown it in two batches, for 3-4 minutes, to get a lovely bit of colour on it. Remove from the pan and set to one side.
Reduce the heat to medium and add the onions to the pan. Stir well. If the pan looks a little dry, with lots of caramelisation on the bottom, add a splash of water to loosen it, and then mix well and cook the onions, stirring occasionally, for 5-6 minutes until soft.
Chuck the tomatoes, tomato purée, cinnamon, turmeric, saffron, lamb, split peas and stock into the pan, with a pinch of salt and a teaspoon of ground black pepper. Mix well.
Pop the lid on the casserole and put it into the oven for 75-90 minutes, or until the meat is soft and tender and the split peas are cooked. If it looks a little dry when you check it, add a splash more water.
Add the lime juice and parsley and mix well. Check the seasoning. Serve immediately with rice and extra parsley.