Cut the cabbage in half and soak in salted water for 15 minutes. Agitate and drain well. Shred the cabbage.
Heat the bacon fat or butter in a large, heavy skillet and add the diced potatoes. Cook over medium heat until lightly browned. Add 2 chopped onions and cook until transparent, about 5 minutes.
Add cabbage and toss well with two wooden spoons, a la stir-fry. When the cabbage starts to wilt, add salt and freshly-ground black pepper to taste and a splash of that beer in your left hand and about 1 T wine vinegar. Cover, with lid slightly askew, and simmer over low heat until tender (about 30-45 minutes).
* Cabbage and Potatoes -- With a nod toward Nancy Mintz who reminded me how good cabbage can be, especially in the winter time when other fresh veggies are scarce. This recipe serves 8, and is good hot or cold.
* Like Nancy said, one cabbage goes a loooonnnngggg way, so I usually use a quarter to a half a head when cooking for 2.