Here in Germany and in most of central Europe it is very popular in winter and, because it goes well with dark meat and game is considered obligatory at the Christmas dinner table or with the St Martin's day goose.
However, it is also a favourite every day veg and people say that it tastes better when re-heated. When I asked a Belgian colleague, she said that it counts mainly as a weekday dish there and would be served with sausages or such.
When I was an au pair, I learned to cook it this way:
Boil the whole head of the cabbage for about 45-50 mins (depending on size) and then cut it into strips. Cook the cabbage in a closed saucepan with: Strips of onion, chopped apple, a pinch of sugar, salt and a shot of vinegar.
I've never cooked it like that myself since, but cut it up raw (on the bread slicer, and wearing rubber gloves - it stains like mad), then cook in a closed pan on a low heat with the other ingredients as given above. It needs no water. I'm never sure how long to cook it, but the colour should have pervaded the cabbage pieces, which have white edges when first cut. (The apples and onion will be dark red, too) You can't cook it too long or too often.
Some recipes I have tried include adding raisins, port wine, or red wine. All are nice, especially for a special Christmas or Boxing Day meal.
Maybe the vinegar is to counteract the heavy meat you eat it with, but it is always included. You can't really taste it once it's cooked for a while. Malt vinegar is unknown outside the UK so we're talking wine or cider vinegar here.
In our part of Germany it's called Rotkraut (red cabbage) but it's also known as Blaukraut (blue cabbage) - actually it's purple - but "Blaukraut" gives rise to a few tongue twisters, so it's stayed in the language for that reason!