Chef's Note: You can replace the turmeric and masala powder with curry powder
1. In a large cooking pot, heat the oil and add the chopped onions, frying until golden brown. Stir in the turmeric and masala powder (or curry powder), garlic and chiles, mix well and cook for a couple of minutes to integrate flavors. Add the lamb and sear on all sides. Sprinkle the flour over the meat using a sifting motion, spoon in tomato paste, then gradually add the stock (or water) stirring constantly while doing so. Reduce the heat, cover and simmer over low heat until meat is tender, about 1 hour.
Check the pot often and stir so the curry doesn't burn. If the sauce is thickening too fast during this cooking time, add water to retain the consistency and to prevent burning. (If you prefer, once you have added the stock or water and the sauce is a good smooth consistency, you may transfer to a covered roasting pan and finish in the oven at 350 degrees F until the meat is tender.) In the last 30 minutes of cooking time, stir in the potatoes.
2. While the lamb curry is in its last 1/2 hour, bring 5 cups of water to a boil, add rice and salt, reduce heat, cover and cook until tender, about 20 minutes. Remove from heat and let sit 5 minutes.
3. Spoon rice onto serving plate, top with lamb curry and garnish with fresh cilantro.