1.Cover chickpeas and split peas with cold water in a large bowl. Soak overnight; drain, then rinse.
2.Combine paprika, half the ground coriander, half the cumin, 1 tbsp of the oil and lamb in a large bowl. Cover; refrigerate 3 hours or overnight.
3.Heat 1 tbsp of the remaining oil in a large saucepan over low heat. Stir onion, garlic and ginger over heat until onion softens. Stir in turmeric, garam masala, chilli and remaining ground coriander and cumin. Continue stirring until fragrant.
4.Add peas, tomato and the water; bring to the boil. Reduce heat and simmer with lid on, stirring occasionally, for 1 hour or until dhal is tender. Remove from heat and stir in fresh coriander. Season to taste.
5.Meanwhile, heat remaining oil in a large frying pan over high heat. Cook lamb, 3 minutes each side or until browned and cooked as desired. Remove from pan. Cover and rest 10 minutes, then slice thickly.
6.Serve lamb with dhal.