1. Tip the rice into a bowl. Add enough cold water to cover. Set aside.
2. Peel and finely chop the onion. Set a frying pan over medium heat. Add a splash of oil to the pan. Swirl in the onion and a pinch of salt. Cook for 5 mins, or till translucent.
3. While the onion cooks, finely chop the mushrooms. Add to the onions. Cook 5-10 mins or till they pick up a little colour. Add the cumin, cinnamon, a pinch of chilli and the venison mince.
4. Turn the heat to high. Sizzle till the meat is nicely browned, stirring to break up any lumps. Season with salt and pepper, to taste.
5. Drain the rice. Add it to the meat (the rice will cook as you steam the filled parcels). Take off the heat. Roughly chop the parsley and walnuts. Add to the meat mixture along with the cranberries and the zest of 1 lemon.
6. Bring your stock to the boil. Trim the base off your cavolo nero leaves so they're roughly 18cm long. Plunge the leaves into the stock (you may have to do this in batches). Remove with tongs or a slotted spoon, saving the stock for later. Let the leaves cool for a moment. Then, start filling.
7. For each dolma, add 1 heaped tbsp of filling in the centre of one leaf. Roll up securely, folding the mix over the sides as you roll. If the filling tries to escape from the sides, roll another leaf around the parcel, in the opposite direction, to cover the sides.
8. Arrange the stuffed parcels, seam side-down, in a large lidded pot coated with enough olive oil to fully coat the base. Create a double layer of dolmades if you need to.
9. Set a sieve over the top. Squeeze the juice from the zested lemon over the dolmades (the sieve will catch the pips). Pour enough stock over to just cover. Bring to the boil. Lower the heat. Pop a lid on. Simmer for 1 hr.
10. Carefully remove the steamed parcels from the pot, allowing 2-3 per serving. Spoon any excess broth over, too. Delicious on their own with fresh lemon slices, or serve with a splash of chilli sauce, or garlicky crème fraîche.