Season the knuckles of lamb from all sides with salt and pepper. Clean, peel, wash and roughly chop the vegetables. Peel the shallots and garlic, halve both.
Heat 2 tablespoons of oil in a frying pan. Sauté the lamb knuckles in it on all sides over high heat. Take them out. Sauté the vegetables, shallots and garlic in the frying fat all around. Stir in the tomato paste and sweat briefly.
Deglaze with wine and stock. Wash and add rosemary and bay leaf. Add the lamb knuckles again and braise covered for about 2 hours. Turn the knuckles every 30 minutes.
In the meantime, wash and roughly chop the basil for the pesto. Grate the parmesan. Coarsely chop the pine nuts. Puree coarsely in a mixer with 150 ml olive oil. Season with salt and pepper.
Take out the lamb shanks. Pour gravy through a fine sieve into a pot and let it boil down for about 10 minutes. Put the vegetables with the knuckles back into the roaster and keep them covered and warm.
Stir cold butter into the gravy in small pieces one by one until the sauce has a binding effect. Season to taste with salt and pepper. Arrange knuckles with vegetables, gravy and pesto. Roast potatoes taste good with it.