1. Preheat oven to 250 degrees Fahrenheit (120 degrees Celsius).
2. Using the large holes on a box grater or food processor, grate the onion until you have two cups of grated onion. Mix with honey, balsamic vinegar, and salt.
3. Place ribs in a baking dish and pour sauce over the top. Cover tightly and bake three hours. Uncover and turn the ribs. Continue baking one to two hours until the meat is very soft.
You can make these up to three days in advance and refrigerate, or freeze, tightly wrapped, and defrost in a warm oven until heated through.