Preheat your oven to 325°F (160°C). Season the lamb chunks with salt and pepper, then toss them in the all-purpose flour until evenly coated.

Heat the vegetable oil in a large ovenproof casserole dish or Dutch oven over medium-high heat. Add the lamb in batches, searing until well browned on all sides, about 5-7 minutes per batch. Remove the lamb to a plate and set aside.

In the same pot, add the sliced onions and carrots. Sauté for 5 minutes until the onions are softened and lightly browned, scraping up any flavorful brown bits from the bottom of the pan.

Return the browned lamb and any resting juices to the pot along with the fresh thyme, bay leaf, and broth. Bring the mixture to a gentle simmer.

Remove the pot from the heat. Carefully arrange the thinly sliced potatoes in overlapping concentric circles on top of the lamb and vegetable mixture, covering the surface completely.

Brush the top layer of potatoes evenly with the melted butter and sprinkle with a little extra salt and pepper. Cover the pot with a tight-fitting lid.

Bake in the preheated oven for 1.5 hours. This allows the meat to tenderize slowly in the rich broth.

Remove the lid and increase the oven temperature to 400°F (200°C). Bake uncovered for an additional 30 minutes, or until the potatoes are deep golden brown and crispy on the edges.

Let the hotpot rest for 10 minutes before serving. Enjoy it hot with a traditional side of pickled red cabbage or steamed green vegetables.