Heat oven to 350 degrees F.
In small saucepan, combine the oil, vinegar, sugar, mustard, caraway seeds, salt, pepper and celery seeds. Bring to a boil.
In large roasting pan, combine Savoy cabbage and red onion. Pour the warm oil mixture over vegetables; stir to coat vegetables completely.
Bake in 350 degree F oven for 15 minutes or until the vegetables are wilted. Add the red cabbage; bake for another 10 minutes.
Spoon coleslaw along with any liquid from roasting pan into serving bowl. Serve warm. Makes 6 servings (6 cups).