Heat the oil in a large frying pan, cook the lamb until browned all over for about 10 mins, then remove from the pan. Cook the onion in the same pan until golden brown, about 5 mins. Stir through the ginger, garlic, cumin and coriander, then cook for 2 mins more until you smell the spices. Return the lamb to the pan, pour over the tomatoes, bring to the boil, then leave to simmer over a gentle heat for 11⁄2 hrs until the meat is really tender. Top up with a little boiling water if the sauce becomes too dry. Add in the chickpeas and garam masala, then simmer for 5 mins more. Stir through spinach and cook until wilted slightly then season to taste.
STEP 2
Meanwhile, bring a large pan of lightly salted water to the boil and cook the potatoes until softened, about 15 mins. Drain and mash. Stir through the curry paste and yogurt, and serve alongside the curry.
