This is a very simple side dish that can be made with any kind of cabbage. I like the white Savoy type myself.
1 large onion sliced into slivers (substitute leeks if that is your preference)
1 medium head of cabbage cored, rinsed and thinly sliced
2-3 Tbls of butter
Salt and pepper to taste
Heat a skillet on medium high. Add the butter and when it has melted add the onion. Cook, while stirring frequently until translucent. Add the cabbage and cook until wilted. Add salt and pepper to taste. (For a twist add some white wine when you add the cabbage. In western Pennsylvania they eat this with egg noddles for a main dish).