Roasted Sweet Onions with Balsamic Vinegar

Preheat over to 350 Degrees F. Rub onion halves with olive oil. Sprinkle halves on both sides with salt and white pepper. Place onions, cut side down, in a large skillet that can go into the oven. Baken onions until soft, about an hour. With a spatula, scoop up onions and place them in a serving dish, cut side up. Place water, vinegar, brown sugar and butter in same skillet that onions were roasted in. Srape skillet to dissoslve brown, baked-on juices from onions. Heat to boiling. Boil a minute to reduce, then spoon mixture over each onion. Taste and add more salt if necessary. Serve hot.