This is a typical peasant-dish and you can (and really should) use the cheapest cut of lamb. Traditionally, this dish was made with deboned lamb’s neck. If you slow-cook this combination of meat, muscle and marbled fat, you get a tender, tasty and moist dish. If you cannot pursuade your butcher to debone some neck for you, then boneless shanks or shoulder (lean) whould be good substitutes. The kidneys add to the flavour and economy of the dish but if you do not eat offal, just add 200 g more lamb or tender pork.
Heat the oil in a saucepan and brown the lamb pieces and kidneys in batches. Remove from the pan and set aside.
To the same pan, add the onions and salt and sautÚ until the onions are golden. Stir in the flour and add the stock together with the thyme, bay leaves and Worcestershire sauce. Stir and simmer until thickened.
Spray an oven-safe dish with non-stick spray and place a third of the potatoes in the bottom of the dish, season with salt and freshly-milled black pepper. Place the lamb meat and kidneys on top of the potatoes and pour in the onion sauce mixture. Cover with a sheet of oiled baking paper and close with the lid.
Place the dish in the oven preheated to 180║ C for 45 minutes or until the meat is tender but not mushy.
Remove the dish from the oven, remove the paper and lid and arrange the rest of the potatoes op top. Brush or drizzle with the melted butter and return the dish to the oven for a further 45 minutes or until the potatoes on top are golden and cooked.
Serve with lightly-steamed greens such as green beans and broccoli.