Heat the oil in a large flameproof casserole over a medium heat. Add the lamb and fry until golden. Remove from the pan and reduce the heat to medium-low. Add the garlic, carrots, onions and thyme,and cook for 2 minutes. Preheat the oven to 160°C, fan 140°C, gas 3.
Return the lamb to the casserole, add the tomato purée and cook for 2 minutes. Add the wine and stock then bring to the boil. Season with freshly ground black pepper. Put the lid on the casserole and cook in the oven for 2 hours.
Meanwhile, cut thin slices about ¾ of the way through each potato, holding them lengthways. When the lamb has cooked for 30 minutes, put the potatoes on a baking tray and bake for 1 hour 30 minutes.
Remove the casserole from the oven, then take out the lamb and transfer to a plate to rest. Increase the oven to 200°C, fan 180°C, gas 6 and cook the potatoes for a further 10 minutes, until crisp. Strain the liquid from the casserole into a pan and simmer for about 10 minutes.
Meanwhile, bring a pan of water to the boil and cook the kale for 5 minutes, then drain. Shred the lamb using two forks, then serve with the vegetables, kale and sauce.
Love lamb? Try our layered lamb hotpot, perfect for a warming supper. Watch the ‘How-to’ video.