1/2 cup tomato sauce
Rub meat well with seasoning salt, onion powder, garlic powder and black pepper. Heat heavy pan with small amount of olive oil and brown roast well on both sides. This will take a few minutes; don’t rush the browning step.
While roast browns put 1 cup beef stock in saucepan, bring to a boil and cook until reduced to 1/2 cup, then let cool slightly and mix in balsamic vinegar and tomato sauce. Peel onions and cut into thick slices.
When the meat is brown on all sides, remove the meat and then deglaze pan with 1/4 cup water. Add the pan drippings to sauce mixture.
Place onions in bottom of slow cooker. Put meat on top of onions and pour beef stock mixture over. Cook on low for 6-8 hours, until beef is tender. The meat might be partly submerged in liquid after this much time.
Remove meat from slow cooker and cover with foil to keep warm. Drain liquid from Crockpot and remove as much of the fat as you can with fat separator or skimmer. Cook down liquid by about 1/3, and serve sauce with meat and onions.
The leftovers make GREAT sandwiches!!