Preheat the oven to 300 degrees F. Season the roast very generously with salt and pepper, and then dust lightly with the flour.
Put a Dutch oven over medium-high heat, and then add the olive oil. When the oil is hot, add the roast, and brown deeply on all sides, about 4 minutes per side.
Remove the roast to a platter. Stir in the vinegar, shallots, celery, carrots, parsnips and garlic, and then set the roast on top of the vegetables. Pour the chicken stock and bourbon around the meat, cover, and roast in the oven for 2 hours.
Transfer the roast to a cutting board. Spoon the vegetables and pan juices onto a large serving platter. Slice the roast, arrange the meat on top of the vegetables, and serve family style.