Heat the olive oil in a large sauté pan over medium-high heat. When warm, add the onion and stir to coat well. Sprinkle the sugar over and lower the heat to medium. Cook slowly, stirring frequently, for about 20 minutes, so that the onions soften and turn golden (do not let them burn). Add the shredded cabbage, caraway seeds, salt and pepper, and stir to combine. Add a splash of white wine (just enough to moisten the mixture) and let simmer until tender (about another 20 to 30 minutes).