Place a large, flameproof casserole pot over a high heat, add 1 tablespoon of the oil, & brown the lamb pieces in two batches. Remove and set aside on a plate.
Reduce the heat to medium–high, add another tablespoon of oil & fry the carrots, celery, and onion for 4–6 minutes or until the onions have softened. Season with sea salt & ground black pepper.
Preheat the oven to 160°C /325°F/Gas Mark 3.
Return the meat to the pot, along with the bay leaf and stock, season with sea salt & ground black pepper & bring to the boil.
Peel and slice the potatoes into 1cm slices.
Remove from the heat & push the slices of potato down into & across the top of the stew, dot with a little butter & give a final seasoning of sea salt and ground black pepper. Cover and place in the oven to cook for about 1½ hours or until the meat is tender.
Remove the lid, turn up the heat & cook for a further 10 minutes until the potatoes have coloured.
You can serve the stew straight away or leave it covered overnight in the fridge for the flavours to develop, then reheat. Serve in deep bowls & you can also serve with slices of white bread if you want & soak up that gorgeous liquid.
