01 - Preheat oven to 325°F.
02 - Pat the beef chuck roast dry with paper towels. Rub evenly with olive oil. In a small bowl, combine 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 2-3 minutes per side. Remove the roast and set aside on a plate.
04 - In the same pot, add the sliced onion and minced garlic. Sauté for 2-3 minutes, stirring occasionally, until softened and fragrant.
05 - Pour in the beef broth, water, and Worcestershire sauce. Add the Italian seasoning, sliced green bell pepper, and fennel seeds. Scrape up any browned bits from the bottom of the pot to deglaze.
06 - Return the seared roast to the pot. Cover tightly with a lid and transfer to the preheated oven. Braise for 2.5 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 and skim off any excess fat from the surface.
08 - Using a sharp knife or meat slicer, thinly slice the rested beef against the grain. Return the sliced beef to the strained au jus and simmer gently for 5-10 minutes so the meat absorbs the flavorful broth.
09 - Split the Italian rolls or hoagie buns and pile generously with the sliced beef. Ladle extra au jus over the top. Finish with a generous spoonful of giardiniera and roasted sweet peppers. Serve immediately with additional au jus on the side for dipping.