1. Place the rabbit pieces in a bowl, add the vinegar-water mixture, and marinate for 1 hour, turning occasionally. Drain and dry thoroughly with paper towels.
2. In a 10- to 12-inch sauté pan, heat 3 tablespoons of the olive oil over medium-high heat until almost smoking. Add the rabbit pieces, in batches to avoid crowding, and brown, turning once, on both sides, 5 to 7 minutes per side. Transfer to a plate and set aside.
3. Reduce the heat to medium-low, add the onions, and cook, stirring, until limp and light golden. Add the wine and bring to a simmer, then add the rabbit pieces, nestling them among the onions. Cover and cook for 30 minutes.
4. While the rabbit is cooking, heat the remaining 3 tablespoons olive oil in another large sauté pan over medium-low heat. Add the peppers and cook for 15 minutes. Cover and continue to gently stew until thoroughly wilted and starting to brown, about 15 minutes longer.
5. Stir the peppers and their juices into the pan with the rabbit. Add salt and pepper to taste and cook until the rabbit is very tender, about 30 minutes longer. Check the amount of liquid in the pan after 15 minutes–there should be a small amount of rather syrupy oil in the bottom of the pan, just enough to keep the meat and vegetables from burning; add a little more wine, or water or stock if necessary to prevent sticking. Serve immediately.