Pull the meat out of the fridge and let it rest for 20 to 30 minutes at room temperature.
Heat the oil in a large skillet set over medium-high heat. Add the beef chunks to the hot oil and sear for about 4 minutes per side or until browned. Transfer the beef to the insert of your slow cooker.
Return the skillet to the burner. Add a splash of beef broth and, using a wooden spoon, scrape up all the browned bits from the bottom of the skillet. Cook for 1 minute.
Remove from heat and pour the liquid over the beef in the slow cooker. Sprinkle the packet of Italian Dressing Mix over the beef.
Add the pepperoncini peppers, pepperoncini juice, and giardiniera. Season with Italian seasoning and pour in the remaining beef broth.
Cover and cook on LOW for 8 to 10 hours or until the beef is fall-apart tender. You can also cook it on HIGH for 5 to 6 hours.
Remove the beef from the slow cooker, transfer it to a cutting board, and shred it. Return the shredded beef to the slow cooker; cover and cook for 20 more minutes.
Serve the shredded beef on toasted buns with provolone and giardiniera.
Notes
Beef Cut: I used Chuck Roast, but you can also use a Brisket or a rump roast.
Trim Excess Fat: Avoid excessive grease by removing large fat portions before cooking.
Brown the Beef: For optimal flavor, brown the meat first and deglaze the pan to incorporate all the tasty juices.
Soak for Flavor: Immerse the cooked beef back in the liquid in the slow cooker to enhance its juiciness and flavor for an impeccable sandwich.
Storage: Italian beef will last up to 5 days in the fridge in an airtight container. Leftovers can also be frozen for up to 2 months.