1Combine the oil, bourbon, onion, garlic, pepper, mustard, salt and vinegar, blending well.
2Place the meat in a plastic bag or glass dish. Pour the marinade over the meat and marinate 1 hour at room temperature, turning the meat 2 to 3 times.
3Drain the meat, reserving the marinade.
4Spit the meat from end to end through the center or on a diagonal, making sure that the roast is balanced.
5If the meat has not been tied already, tie it after you have fastened it in place with the spit forks--it will be a little firmer that way.
6Engage the spit and turn the meat, 8 to 10 inches above hot coals, for 1 1/2 hours or until a meat thermometer registers 120 degrees for rare, to 2 1/2 hours for well-done, 165 degrees on the meat thermometer.
7Brush with the sauce for the last 30 minutes of cooking.
8To roast on the grill, place the meat over a drip pan with the hot coals surrounding the drip pan, or pushed back.
9Turn and baste the meat as needed to cook evenly.
10Grill 1 1/2 to 2 1/2 hours.
11Let the meat stand, on a platter, 20 to 30 minutes before carving.
12Heat the sauce and serve with the meat.
13NOTE: Any leftovers make great sandwiches and beef salads.