Persian lamb with rhubarb and chelow

1. Heat olive oil and butter in a casserole until foaming, add lamb in batches and stir occasionally until browned (4-5 minutes), transfer to a plate and set aside. Add onion and garlic to pan, stir occasionally until beginning to caramelise (10-12 minutes), then add spices and stir until fragrant. Return lamb to pan, add stock and 500ml water, season to taste and bring to the simmer over medium-high heat. Reduce heat to medium and simmer gently until meat is very tender (2-3 hours). Add rhubarb, simmer until just tender (4-5 minutes), remove from heat, add lemon juice, adjust seasoning to taste. Keep warm.

2.Meanwhile, for chelow, drain rice and rinse under cold running water until water runs clear (3-4 minutes). Bring 1 litre salted water to the boil in a large saucepan, add rice and cook, stirring once or twice, for 10 minutes. Drain in a colander, rinse under lukewarm water, then drain again. Combine yoghurt, 60ml oil, ½ tbsp saffron mixture and 60ml water in a bowl, stir in ½ cup rice and spread in the base of a large saucepan with a lid. Gently mound the remaining rice on top, forming a pyramid. Cover with lid and cook over medium heat for 10 minutes. Combine remaining oil, saffron mixture and 250ml cold water in a jug, pour over rice, and cover with a tea towel then the lid. Reduce heat to low and cook for 50 minutes (do not stir or remove lid). Stand for 10 minutes, then serve with lamb, scattered with mint and coriander.