Preheat oven to 350°F. In a large bowl, stir together soup, sour cream, Worcestershire, vinegar, pepper and garlic powder; stir in green beans, potatoes and 1 & 2/3 cups onions.
Pour mixture into a large cast iron skillet and bake, uncovered, 20 to 25 minutes or until hot and bubbly. Meanwhile, cook and crumble bacon; set aside.
Sprinkle remaining 1 cup onions over hot green bean mixture and bake 5 minutes or until onions are golden brown. Sprinkle with bacon.
Notes
*I've tried this casserole with both whole beans and the French style and while both are delicious, the French style was the voted favorite!