Halve the cabbage, cut the tough stem from both halves of the head. Remove the wilted top layer of cabbage leaves. Slice or grate the cabbage thus prepared.
Peel and finely chop the onion. In a large enough pot, heat the lard and fry the onions in it until light brown.
Move the onion to the side of the pot, sliding the pot if possible, so that the onion part is away from the heating source.
Put the sugar on the free surface of the pot and let it melt; if necessary, increase the heat to speed up the caramelization of the sugar.
Once the sugar starts to turn golden, add the chopped cabbage and mix everything. Don't be alarmed if the sugar forms hard lumps - it will dissolve as the cabbage stews.
Now salt the cabbage, add the caraway seeds, and pour in the vinegar. Stir, turn down the heat. Cover the pot with a lid and simmer at low heat for about 45 minutes.
Remove the lid, raise the heat to be medium and allow any liquid that the cabbage has released to drain. Stir from time to time. Once the liquid has evaporated, and the cabbage starts to fry and stick to the bottom of the pot, you're done! This takes another 30-45 minutes.