The Danes Christmas meal is big on tradition. You won't see many variations on their holiday menu. Served alongside the roasted pork, braised cabbage is almost always present. Here's my version.
1 medium head purple cabbage, outer leaves and core removed, shredded
3 - 4 cups water
salt and pepper to taste
1 T. white vinegar
In a large saucepan with a lid, add shredded cabbage and water. Over medium high heat, bring liquid to a boil, cover and let cabbage simmer for an hour or two until tender. Stir occasionally and don't let the cabbage boil dry. Add additional water if needed.
When cabbage is tender, add salt and pepper to taste and stir in vinegar.