In a large skillet, cook the bacon until crisp. Drain on paper towels, and set aside. Remove most of the bacon fat from the pan and set aside (leave about 1 tablespoon of bacon fat in the pan).
Add water to a 3-quart saucepan, and bring to a full boil. Add the beans, and cook over medium heat, stirring occasionally, until beans are crisp and tender (5 to 7 minutes); drain.
Add the beans to the skillet along with the onion, butter, pepper and salt. Cook over medium heat, stirring occasionally, until the onion is crisp and tender (5 to 7 minutes). Spoon into a serving bowl and sprinkle with the bacon.