01 - Preheat the oven to 325°F. Position the rack in the center of the oven.
02 - Pat the beef chuck roast dry with paper towels and rub evenly with olive oil. In a small bowl, combine the kosher salt, black pepper, dried oregano, dried basil, garlic powder, and crushed red pepper flakes. Coat the roast thoroughly on all sides with the spice mixture.
03 - Heat a large Dutch oven or heavy oven-safe pot over medium-high heat. Sear the seasoned roast on all sides until deeply browned, approximately 2 to 3 minutes per side. Remove the roast and set it aside on a plate.
04 - In the same Dutch oven, add the sliced onion and minced garlic. Sauté for 2 to 3 minutes until softened and fragrant, scraping up any browned bits from the bottom of the pot.
05 - Pour in the beef broth, water, and Worcestershire sauce. Add the Italian seasoning, sliced green bell pepper, and fennel seeds. Stir well and bring the mixture to a gentle simmer.
06 - Return the seared roast to the Dutch oven, ensuring it is partially submerged in the liquid. Cover tightly with a lid and transfer to the preheated oven. Braise for 2½ to 3 hours, or until the beef is fork-tender and easily pulls apart.
07 - Remove the roast from the pot and let it rest for 15 minutes on a cutting board. Strain the cooking liquid through a fine-mesh strainer into a bowl, discarding the solids. Skim off any excess fat from the surface of the au jus.
08 - Using a sharp knife or meat slicer, thinly slice the rested beef against the grain. Return the sliced beef to the Dutch oven, pour the strained au jus over the meat, and simmer gently for 5 to 10 minutes so the beef absorbs the flavorful liquid.
09 - Split the French rolls or hoagie buns and pile the juicy sliced beef generously onto each roll. Ladle extra au jus over the top and garnish with giardiniera and roasted sweet peppers to taste. Serve immediately with a side of extra au jus for dipping.