Lay venison roast out on a work surface or cutting board. Starting at the bottom third of the roast, take a sharp knife and cut through the roast until the cut is about 1 inch from the next side. Do not cut all the way through the roast! Flop the roast open with the large side on the left and the smaller, thinner side on the right. Cut into the thicker side from the "hinge" side where you stopped cutting before. Cut until the knife is about 1 inch from the other side. Again, do not cut all the way through the roast. Press the meat down flat and place in a non-reactive container.
Whisk together vinegar and next 7 ingredients. While whisking, add oil in a thin stream until emulsified. Pour mixture over meat, and turn meat to coat evenly. Cover and refrigerate for 12 hours, turning occasionally. Remove from marinade, roll up roast, and tie up snugly with butcher string.
Preheat oven to 350 degrees. Place roast in a roasting pan, and cook in the preheated oven for 1 ½ hours or until roast reaches 135 degrees in the center for medium-rare. Cooking this roast well-done will result in a much drier, tougher piece of meat. Check internal temperature after 1 hour and monitor internal temperature until it reaches desired doneness.
Allow roast to cool completely. It is best to slice after it has been refrigerated for at least 1 hour.
