These days, we seem to be growing more and more Italian black cabbage in the UK. In Italy it's known as cavolo nero and it is quite a robust leaf; it takes a fair bit of cooking, but it is wonderful when added to soups and stews.
If you can find the little round flat Italian onions (cippolini), then they would be ideal for this dish, but otherwise you could substitute shallots or button onions instead.
250-350g shallots or small onions, peeled
2tbsp olive oil
Salt and freshly ground black pepper
500g black Italian cabbage, trimmed of any thick stalks and cut into 2-3cm chunks
A couple of good knobs of butter
Put the shallots in a pan with the olive oil, just cover with water and season; bring to the boil, cover with a lid and simmer gently for about 15-20 minutes or until the shallots are tender. Meanwhile, cook the black cabbage in boiling salted water until tender, then drain. Drain the shallots and toss in a pan with the cabbage and butter and season to taste.