Mix marinade ingredients together in large pan and place meat into the marinade, turning to coat both sides. Cover with plastic wrap and place in fridge for 4-12 hours. Can flip meat to other side once during marinade time if desired.
Slice onion and place in bottom of crockpot.
Heat oil in heavy skillet, and sear roast on both sides till well browned. Place roast on top of onion.
Sprinkle salt, pepper, thyme, rosemary, oregano, and cayenne on top of the roast.
Dice garlic and place carefully on top of the meat. Arrange sliced butter over top of the garlic, and pour the balsamic vinegar, soy sauce, and broth into the crockpot.
Cover with lid and cook on HIGH for 8 hours. Remove from crockpot and cut against the grain several times. Shred with a fork and place back into the juice. Stir and serve over noodles or potatoes.
Notes
You can omit the marinade if you don't have time, just sear the roast and proceed with recipe.Serve over mashed potatoes or hot noodles. You can also pile onto rolls for a French Dip. Or stuff into tacos with cheese, jalapeños, and sour cream.Serving is approximately 1 cup, this may vary depending on size of roast and amount of meat on the bones, etc.