Peel and chop the onions. Clean the chilli, cut in half, scrape out the seeds. Wash the pods. Peel ginger and grate finely. Crush coriander finely. Cut lamb into cubes. Heat up a roaster or casserole, add 1 tablespoon of oil.
Sear the lamb in it in portions and take it out. Add 250 ml water to the pot and simmer for about 2 minutes, pour back. Heat 2 tablespoons of oil, fry onions until translucent. Add chilli, ginger and spices, fry for 2 minutes while turning.
Pour back the meat water and simmer for 2 minutes. Add tomatoes and meat, season with salt and pepper and bring to the boil. Cover and let simmer for about 1 hour at low heat.
Add the tomato paste and continue to simmer for about 20 minutes. Season to taste with Garam Masala, salt and pepper. Wash the coriander, dab dry and pluck. Sprinkle curry with coriander. Serve with rice.