In a small bowl, combine all the seasoning for the beef.
Cut beef into cubes and lightly coat with 1-2 tbsp oil and beef seasoning. Save any leftover seasoning.
Heat 1 tbsp of oil in a large pot over medium heat. Cook the beef in batches for 1-2 minutes per side or until golden brown. Remove cooked beef from the pot.
Add 2 tbsp of butter and ΒΌ of the beef broth to the pot. Deglaze the pan by gently scraping up the brown bits. Add onions and cook for 3-4 minutes or until lightly soft.
Stir in garlic, the remaining beef broth, leftover seasoning, thyme, rosemary, beef, and jar of sliced pepperoncini peppers.
Cover with a lid and simmer on low for 3-6 hours.
Remove thyme and rosemary springs. Shred beef with two forks and leave it in the broth. Taste and adjust seasoning if necessary.
Serve hot beef on hoagie rolls, topped with provolone cheese and mayo if desired.