1. Marinate the rabbit pieces in red wine and vinegar overnight.
2. Remove rabbit from marinade, pat dry, and set aside. Reserve the marinade.
3. In a large pot, melt butter over medium heat. Add rabbit pieces and brown on all sides.
4. Remove rabbit and set aside. In the same pot, add onions and garlic, and cook until softened.
5. Sprinkle flour over onions and garlic, stir well, and cook for another minute.
6. Gradually add the reserved marinade and beef broth, stirring constantly.
7. Return rabbit to the pot, add salt, pepper, and juniper berries. Bring to a boil, then reduce heat and simmer for 2 hours.
8. Serve hot with your choice of side.