Preheat oven to 275 degrees. To a large Dutch oven over high heat, add olive oil and heat until shimmering and very hot. Season your chuck roast with salt and pepper and add to the pot. Sear both sides until there is a nice brown crust, about 3-5 minutes per side.
Remove the chuck roast from the pot and lower the heat to medium. Add the onion slices and cook until the start to soften and brown slightly, about 2 minutes. Add the garlic and cook until fragrant, about 1 minute.
Add the roast back to the pot, along with the beef broth, tomato sauce, pepperoncini peppers, 1/2 cup of liquid from the pepperoncini jar, Italian seasoning, and bay leaf. Add about 1 tsp EACH of salt and pepper.
Gently stir, cover with a lid, and place in the oven. Cook for 3-5 hours until the roast is very tender and the meat is falling apart.
Remove the pot from the oven and then carefully remove the roast from the pot to a cutting board. Shred the meat, discarding any fatty pieces, and place the meat back in the liquid. Serve as a sandwich, over pasta, or mashed potatoes. Enjoy!