Peel the onion and cut into quarters. Place half of the onion in the bottom of the slow cooker. Peel and slice the garlic.
Combine the salt, pepper, garlic powder and onion powder in a small bowl.
Rub the olive oil all over the roast, then sprinkle with the spice mix.
Heat a large skillet (preferably cast iron) over medium-high heat. Sear the roast for 1-2 minutes on each side, then transfer to the slow cooker.
Pour the broth and soy sauce around the sides of the roast. Place the garlic and remaining onions on top.
Cover and cook on LOW for 7-8 hours, or on HIGH for 5-6 hours. If the meat does not shred easily after the cooking time is up, cook for an additional hour.
Transfer meat to a cutting board and shred with two forks. Strain the juices and reserve for serving as a dip. Serve on split french rolls, or over pasta, rice or mashed potatoes. Store in an airtight container for later use.
For sandwiches: Preheat the oven to 350 degrees F. Arrange the rolls on a baking sheet and heat for 5 minutes, with the rolls split open so the insides get nice and toasty. Switch the oven to broil, stuff with the beef, top with cheese and broil for a few minutes, or until the cheese is bubbly and starting to brown. Sprinkle with a little fresh parsley before serving. Serve with strained juices from the slow cooker.
This recipe will make about 6-8 cups of shredded beef, which will yield 6-8 generous sized sandwiches. Storage - Leftover beef can be stored in an airtight container in the fridge for up to 5 days. For best results, I would store the beef and hoagie rolls separately so the buns don’t get soggy.Reheating - The shredded beef can be reheated in the slow cooker on low for about an hour or two until warm, in a pot on the stove, or on a sheet pan in the oven.