In a pot, saute the onion in the vegetable oil until soft. Add the cabbage and salt, and cover. Steam over medium heat for 10 minutes.
Remove the cover, and add the apples.
In a small bowl, mix the vinegar and sugar, and pour over the cabbage. Sprinkle with the caraway seeds, mix and simmer, covered, stirring occasionally, for about 30 minutes or until the cabbage is soft. Adjust the seasonings to taste.