Lamb Stock (get this going before you start with everything else)
Place the bones and water in a large saucepan or stockpot and bring to a low boil. Skim off any scum as necessary.
Leave to simmer for 30 minutes, then strain and use in the recipe.
Let's make the Meatballs
Place the mince into a large food processor, along with the salt and cardamom. Do this in batches if your food processor isn't big enough.
Process on medium for about 30 seconds, scrape down, then another 30 seconds.
Scrape down again, and repeat the process: 30 seconds, scrape down, another 30 seconds. This should do it. At this point, you'll have a fairly homogeneous looking lamb paste.
Form balls weighing about 40g (1.5 oz, rounded up) with the meat paste, wetting your hands often to prevent sticking. Set aside until needed. Can also be frozen raw. In the image, the middle ball is for rista.
The Saffron and Mawal Water (or just Saffron Water)
If you've got mawal or cockscomb flower, place the flower heads in a bowl and pour half a cup boiling water over them. Leave to soak for 5 minutes. (Get your dry spices ready in the meantime). If you are not using mawal, go to the saffron step below.
After 5 minutes, drain using a very fine sieve.
Add the saffron to this red water (or just hot water, if not using mawal). Crumble the saffron threads as you add them. Leave aside until needed at the end of the recipe.
Let's cook the Rista
Heat the ghee in a large saucepan or dutch oven on medium-high heat and brown the meatballs. Do this in batches if you have to.
Lower the heat to medium, then add the cloves, green cardamoms, Kashmiri chilli powder and turmeric and give it all a good stir, no more than 10 seconds as the spices will burn.
Add the garlic and fried onion paste and give it another quick stir. But be fairly gentle as you don't want to break the meatballs up.
Add the lamb stock, stir and bring to a boil. When it's come to a boil, lower the heat right down, cover, and cook for 1 hour.
At the end of the hour, add the saffron-mawal water, stir and bring back to a simmer. Leave it to simmer for 1 minute, and check to see if you need any salt (this depends on the stock you used).
Finish off with some freshly ground black pepper, turn the heat off and leave to rest for 5 minutes before serving with rice or roti.
Notes
Total time does not include the lamb stock (which is only 30 minutes), nor the fried onion paste, which I'm assuming will be done earlier.