||Place the lamb leg in a bowl and pour over the buttermilk making sure that all the lamb in submerged. Add cumin powder, coriander powder, chili flakes, fennel seeds and 1 tablespoon of olive oil. Mix all lightly and set aside.
||To make the dal, in a medium non-stick pot, lightly roast the mustard seeds, cardamom, ginger and garlic until their aroma is released. Then, add pepper and tomato paste. Stir gently for a minute. Next, add the dal and fry for 2 minutes, stirring often, until fragrant. Add the tomato paste, onions, shallots, stirring from time to time, adding a tablespoon or so of water to the pan so that the mixture doesn’t stick to the bottom. Cover with the lid and cook for another 10-15 minutes.
||In a medium saucepan, heat oil. Lift the lamb out of the marinade and lay it on the pan. Cook until both sides are browned.
||Return the dal to the heat just before serving and add the spinach leaves. Stir for 30 seconds, just to wilt the spinach, then add the red chilies, butter and salt. Top with the lamb leg, spoon onto individual plates and serve immediately.