Preheat the oven to 160C/320F/Gas 2.
Heat a large casserole dish until hot, then add the olive oil.
Add the onions, garlic and thyme and cook for 3-4 minutes.
Remove from the casserole dish and set to one side.
Place the chops into the casserole dish and seal on each side until golden brown.
Place the onion mixture on top of the browned chops.
Pour over the stock - just enough to cover the lamb and onions.
Meanwhile, heat the vegetable oil or clarified butter in a large pan. Add the potato slices and blanch for 30 seconds.
Drain and arrange the slices on top of the onions and lamb.
Dot the butter over the top of the potatoes.
Place in the oven for one and a half hours, until golden and tender.
For the cabbage, place the vinegar and sugar into a saucepan and bring to the boil, stirring occasionally.
Reduce the heat and simmer for 5-10 minutes, until the liquid is reduced by a third.
Place the cabbage in a large bowl and pour over the vinegar and sugar.
Toss to coat and place in the fridge for 24 hours, stirring every couple of hours.
Serve with the lamb.