Prep the veg and the bacon - Wash and trim the green beans. Cut them into 2-inch pieces. Peel the onion and cut it in half, pole to pole. Slice into 2-inch pieces. Cut the bacon into bite-sized pieces.
Sauté the bacon and onions - Add the bacon and onions to a skillet along with 1 T olive oil. Sauté until the onions are very soft, but not yet caramelized. The bacon will look a bit flabby. If it bothers you, look away!
Add the beans and simmer - Stir in the green beans and add the water. Cover, and simmer for 30 minutes or so. When the beans are thoroughly cooked, really, really cooked, add the vinegar. Simmer for 5-10 minutes longer