In a large skillet, heat olive oil over medium-high heat. Sprinkle roast with salt and pepper and cook until seared on both sides, about 3 minutes per side.
Transfer to a slow cooker.
Slice onions thin, and mince garlic, and add to now empty skillet, cook for about 3-5 minutes, until slightly browned.
Add to slow cooker along with all the slow cooker ingredients (soy sauce, Worcestershire sauce, brown sugar, liquid smoke, beef broth, dry minced onions, beef bouillon, onion powder, dried oregano, salt, pepper, dried thyme, bay leaf).
Cover and cook on LOW for 4-5 hours.
Remove roast from slow cooker, and slice into thin pieces, against the grain. Return to slow cooker for an additional 1-2 hours.
Cut sourdough loaf in half and generously spread butter on each side. Add sliced roast beef, and cheese slices, and strained onions (if desired), to the bottom loaf and top with the remaining half.
Heat oven to 375 degrees.
Place on a baking sheet and bake for about 5 minutes, until cheese is nicely melted.
Take the liquid left in the slow cooker, and strain it over a bowl.
Use the broth that was strained into the bowl as the au jus to dip the sandwiches in. Enjoy!
Servings 6
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.
If you have a Cobs Bakery nearby, the Vienna Sourdough Loaf is AMAZING for this recipe!