The last time I roasted a shoulder of lamb, I had smothered it with such a delicious marinade that I wanted to serve the resultant sauce separately, rather than allow it to be absorbed by surrounding potatoes. Last weekend, I decided to cook potatoes with the lamb. They would need, I thought, a slightly higher heat than the bottom of the oven -- as used for the previous dish -- would provide; but I still thought that my lowest oven setting would do the job.
How do you guess how long a joint of meat will take to cook in a low oven, when all the books give timings for gas mark 4/180 C and above? I had a half shoulder; I hazarded a guess at four hours, with the security of knowing that this joint, being fatty, can take long cooking without drying out. I rubbed a little olive oil over it, and sprinkled it with salt, pepper and chopped garlic. I put it in a roasting tin in the centre of my oven, with a sprig of rosemary on top, at the "S" setting, which my oven thermometer tells me is 130 C.
The potatoes did not need so long. For this dish, I often do not parboil them first -- the slimy toughness of the starchy surfaces is quite pleasant, I think. The drawback is that they are more likely to stick to the tin. This time, to get rid of that sticky starch, I sliced the potatoes into a saucepan of cold water, brought the pan to the boil, allowed it to simmer for a minute or so, and drained.
With an hour of cooking time left, I took the lamb out of the oven, transferred it to a board, tipped the potatoes into the tin, turned them in the juices, put the lamb back on top, and returned the tin to the oven. An hour later, I took out the lamb and transferred it to a warm dish, which I left in the warm grill section. The potatoes were starting to brown, even at that low heat; and some of them were stuck -- perhaps because the sauce caramelised? I turned them, and put them back into the oven at gas mark 7/220 C to crisp. They took about 20 minutes.
This dish comes without gravy, of course. I don't think it needs it.