Turn the oven to 200C/180C fan/gas 6.
Pat the lamb all over with kitchen paper and, using a sharp knife, make slashed in any thick fat areas of the meat.
For the spice mix: put the crushed coriander seeds, paprika, cinnamon, ginger and the cumin seeds into a metal roasting dish with the oil, the garlic cloves, 2 sprigs of rosemary, the bay leaves and a few teaspoons of flaky salt and crushed black pepper, then mix well.
Place the shoulder in and rub the spice mixture all over it evenly and leave it, fattest side facing down. Add 125ml warm water and place in the centre of the oven then turn the heat down to 170C/150C fan/gas 3. Cook for 90 minutes.
For the cauliflower in a medium bowl mix the cumin seeds and olive oil with the turmeric and a little salt and pepper. Slice the cauliflower 1 to 2 cm thick and mix with the turmeric mixture. Lay on a baking tray lined with baking parchment and roast for 5-8 minutes, at the top of the oven until coloured and barely cooked. Remove it and put to one side.
Once the lamb has been cooking for 90 minutes, cut the pears into quarters, remove the cores and add to the roasting dish, turning the shoulder over and basting it. It will take another 1.5 to 2 hours to cook.
For the potatoes: boil the potatoes in lightly salted water for 8-10 minutes or until cooked, then drain. Remove the rosemary leaves from the stems and place in a medium pan with the butter and cook over a moderate heat until the rosemary sizzles, then add the cream, some salt and pepper and bring to a simmer. Mash the potatoes, mixing in the rosemary cream as you do and taste for seasoning. Keep warm.
For the kale: place the butter in a wide pan with a little salt and pepper and 65ml water. Bring to the boil and once the butter has melted add the kale and leek. Place a lid on the pan and cook over a high heat for 5 minutes, stirring the kale every now and then. It’s cooked when it has a little bite but is also tender. Turn the heat off and keep in a warm place in the pan – you’re going to need the pan liquids for the gravy.
Once the lamb is cooked, take it and the pears from the pan, keeping the juices and fats in the pan. Cover the lamb and you’ll need to rest it covered with foil and a tea towel for 10-20 minutes.
. Place the tray of cauliflower back in the oven, but turn it off.
. To make the gravy: place the roasting pan on the heat (or pour the pan juices into a pan) and scatter the flour over the top, stirring it well to avoid lumps. Bring to a sizzle then add the cooking liquids from the kale a little at a time, and bring to a boil. Once it’s the thickness you like, turn the heat to low and simmer for a minute to cook the flour. Taste and adjusting the seasoning if necessary.
. Carve the lamb, mix the mint with the cauliflower, and you’re ready to serve.