I made this for Memorial Day, and it disappeared. The meat is moist and melt in your mouth tender. This roast does just fine in a cast iron skillet browned on top of the stove, and finished in the oven.
Mix the vinegar, oil, mustard and spices together.
Rub this all over the roast, pour whatever is left on the roast and let it marinate for about 20 minutes, or while the coals are getting hot.
When the coals are hot, sear the roast on each side about 5 minutes, then put in indirect heat, cover and roast about 20 minutes or until a instant read thermometer reads 165. Remove from the grill, and let rest a few minutes before cutting.
If you are going to be doing this indoors, then heat an iron skillet on the stove top, brown all sides of the roast, then put in the oven for the rest of time, about 20 minutes.