In a small bowl, mix the minced garlic, onion powder, garlic powder, salt and pepper together. Pat the meat dry with paper towels, then rub the blend over the entire outside of the roast.
Place the wine and the beef broth in the slow cooker and stir in the tomato paste until fairly well blended. Place the roast in the slow cooker, fattier side up, and add the chopped onion on top. Cook on low for 10 hours until the meat is fall apart tender. Remove from the slow cooker and let sit for 15 minutes.
Slice (it will fall apart as you do — that’s a good thing!) and place on a serving platter. Spoon some of the cooking juices with the cooked onion over the top.