Step 1In a heavy pot heated over medium-high heat until hot, add the oil, then the lamb, onion and garlic, stirring until the mixture is browned but careful not to burn, 20 to 30 minutes.
Step 2Stir in the salt, pepper, turmeric, bay leaves and mixed spices, along with the water. Cook, covered, at a gentle simmer until the lamb is tender, 3 to 4 hours. (While the lamb is simmering, prepare the rice.)
Step 3Remove from heat and separate the bones and fat from the meat when it is cool enough to handle. Add the saffron and the lime or lemon juice to the meat and set aside.
Step 1Peel and thinly-slice the onions. In a large skillet heated over medium-high heat until hot, add ¼ cup oil. Add the onions and cook, stirring frequently, until browned, 25 to 30 minutes. Stir in the raisins, dates and advieh and fry until fragrant, about 30 seconds. Remove from heat and stir in 3 tablespoons dissolved saffron.
Step 2Clean and wash the rice several times in warm water, then drain well. Meanwhile, in a large non-stick pot, bring the water and salt to a boil. Add the rice to the water. Bring the water to a boil over high heat, stirring the rice once. After 5 minutes, add the noodles and stir the mixture once to loosen the rice grains and noodles. Boil again until the rice has risen to the surface, about 5 more minutes. Remove from heat, pour the rice and noodles into a colander and rinse with cold water.
Step 3In the bottom of a non-stick pot, combine 1/8 cup oil with ½ cup hot water and the remaining tablespoon of the dissolved saffron. Place a layer of rice and noodles in the pot, add a layer of the raisins and dates mixture. Repeat the layers, arranging the rice in the shape of a dome. Cover and cook over medium heat until the steam rises to the top, about 10 minutes.
Step 4Use the handle of a wooden spoon to poke a few holes (steam vents) in the rice. Mix the remaining oil or butter with the remaining water and pour over the rice. Cover the top of the pot with a dish towel, wrapping the towel over the lid (this will absorb extra steam as the rice cooks) and cover the pot firmly, cooking the rice over low heat until the rice grains are long and tender but not mushy, 50 to 60 minutes (the crust at the bottom of the pot, tahdig, will be thicker and crispier if cooked longer).
Step 5Transfer the rice to a platter and arrange pieces of lamb around it.