This was just messing about, but it turned out to be divine.
Mix redcurrant jelly and mirin in a small saucepan and simmer for a while.
Brush on lamb and baste during cooking.
Serve with the glaze from the cooking process drizzled over.
The lamb: it really does just depend. I find that anywhere between half and a whole rack is for two people. How greedy are you? How many vegetables are you having?
At any rate, you preheat the oven to at least 220C and don’t cook for too long. Ten minutes might be enough for a half rack divided into two serves. It really should be rare. If you want to overcook it, I suggest there is no point cooking such a delicate and expensive cut of meat.