Cut roast in half (optional). Coat a deep skillet with fat and brown meat on all sides over medium-high heat. Place meat in a large ovenproof pan. Add broth, onion, and celery around roast; season with salt and pepper. Cook covered in 375 degrees F oven for 2-½ to 3 hours or until fork-tender. You can either place vegetables around roast for the last hour of cooking or wait until the roast is done, remove it (keeping it covered and warm), then add carrots and potatoes and cook, covered, until tender, approximately 45 minutes. Remove meat and vegetables from cooking pan and keep warm while you make a flour-thickened gravy from the juices.