Fill a saucepan with water and bring to the boil. Peel and cut the potatoes into thin slices about 0.5cm thick and cook in boiling water for 8-10 minutes.

Meanwhile, heat frying pan over high heat and dry fry (without oil) the diced lamb for 5 minutes until browned on all sides.

Clean, trim and slice the leeks and chop the rosemary. Using the oil, add the leeks and rosemary to the pan and fry for 2-3 minutes until the leeks are a little soft.

Make up the gravy according to the instructions, add to the pan and gently stir to combine. Simmer until the lamb is thoroughly cooked, around 20 minutes. Season with black pepper if desired. Transfer mixture to an ovenproof dish.

Preheat the grill. Drain the potato slices and allow to cool. Arrange the potato overlapping until the whole dish is covered in in a single layer. Melt the butter and brush over the potato slices.

Grill for 5 minutes, until golden brown and bubbling. Fill a saucepan with cold water and add the green beans, bring to the boil and cook for 5-10 minutes until soft. Drain and discard the water. Divide the cooked hotpot between four and serve with the vegetables.