Rinse the rice until the water runs nearly clear, then leave the rice to soak in 5 cups of cold water while moving on to step 2, or at least 15 minutes.
Heat oil in a large frying pan over medium high heat. Add the sliced onion and fry until softened, about 5 minutes.
Add the lamb and sauté for an additional 10 minutes, or until the meat starts to brown.
Add the green beans followed by the carrots and sauté for an additional 10 minutes, or until the green beans have started to soften.
In the middle of your pan, add the tomato paste and allow it to fry for one minute, before adding the spices (turmeric, cumin, cinnamon) and salt and pepper. Stir together until spices become fragrant.
Add the bone broth, and allow to cook for about 15 minutes, or until the meat and vegetables are fully cooked through and most of the liqiud has evaporated.
Remove the green bean mixture from the heat, and add rose water and lemon juice. Adjust seasoning for salt and pepper.
Strain the soaked rice.
In a large heavy buttomed or nonstick pot, bring 8 cups of water to a boil. To the boiling water, add 3 tablespoons of salt along with the rinsed basmati rice and cook until rice is al dente (which is typically 5-8 minutes after the water comes back to a soft boil).
Drain the rice thoroughly in a colander and set aside.
Prepare for the first layer of your rice dish by mixing together 1.5 cups of the rice with ⅓ yogurt.
In the large pot, add 5 tablespoon of oil, then layer the yogurt rice mixture on top, and top with ½ cup of the plain parboiled rice.
Loosely layer half of the meat and green bean mixture on top. Follow with a layer of rice, and repeat layering with the remaining green bean mixture.
Using a long handle, make several holes in the rice.
Cook on medium high heat for 3 minutes, then pour over ⅕ cup of hot water mixed with 2 tablespoons of melted butter.
Place clean kitchen towel or paper towel in between the lid and the rice.
Set the temperature to low and cook for about 45 minutes.
When the rice is cooked, remove the lid, and optionally, add a few tablespoons of saffron water to the top of the rice. Serve the rice on a platter, and the tahdig next to it. It is easier to remove the tahdig when it gets slightly cooler.