1. Cook green beans in boiling salted water to cover in an 8-quart soup pot 8 minutes or until tender. Drain, and set aside.
2. Cook bacon in a large skillet over medium heat until crisp; remove bacon from skillet with a slotted spoon, reserving 3 tablespoons drippings in pan, and drain bacon on paper towels. Set aside.
3. Sauté bell peppers and onion in hot bacon drippings 3 to 5 minutes or until tender. Whisk in vinegar, sugar, salt, and pepper. Cook over low heat, stirring constantly, until sugar dissolves.
4. Toss reserved green beans with bell pepper mixture, and transfer to a serving dish. Sprinkle with reserved bacon.