Fry the lardons until they’re lightly browned then transfer to a casserole dish. In the residual bacon fat, fry the diced onion and garlic then add this to the casserole dish. Toss the steak into well-seasoned flour, brown it in the frying pan before also adding to the dish.
Deglaze the pan with the wine then add the mustard. Stir and add to the meat with the bay leaves and beef stock. Cook the casserole for 1.5 hours or until tender.
Meanwhile, skin the shallots and fry these in the butter and sugar with a drop of water until caramelised; reduce the heat then cook until tender. When the meat is tender, season to taste and add the shallots. Leave the whole dish overnight to cool then re-heat the following day. Serve with roasted new potatoes and crusty brown bread.