Cut the lamb into 4 cm cubes. Peel and slice the onions and the white part of the leek. In a heavy-based pan, brown the pieces of lamb with the onion and leek in the butter. Add the flour and cook for a further 5 minutes. Deglaze with white wine and allow to reduce until the liquid has completely evaporated.
Cover with water (2 cm above the meat), add the bouqu