Heat oven to 350°. Heat oil in 10-inch nonstick skillet over medium heat. Cook bell pepper in oil 8 to 10 minutes, stirring occasionally, until tender. Stir in brown sugar and vinegar. Cook 1 to 2 minutes or until pepper is glazed.
Meanwhile, place cheese in ungreased decorative ovenproof plate or shallow ovenproof serving bowl. Bake 10 to 12 minutes or until soft.
Spoon bell pepper mixture over cheese. Sprinkle with onions and nuts. Serve with crackers.