Let the 3-4 pound chuck roast sit out at room temperature for 15 minutes. Generously season the roast all over with salt.
Heat a large skillet over medium-high heat, then add 3 tablespoons vegetable oil. When hot, sear the roast on all sides until golden brown. Cook long enough to develop a crust, about 10 minutes total. Transfer to the slow cooker.
Add a splash of beef broth to the skillet and deglaze the pan. Then, pour 1 cup low sodium beef broth and the pan fond over the beef.
In a small bowl, mix 1 tablespoon Italian seasoning, 1 tablespoon granulated sugar, 2 tablespoons salt, 1 1/2 teaspoons garlic powder, 1 teaspoon onion powder, 1/2 teaspoon black pepper, and 1/2 teaspoon dried parsley. Sprinkle all over the beef.
Add 4 ounces pepperoncini pepper slices and 1/4 cup pepperoncini brine to the slow cooker.
Cover and cook on LOW for 10 hours - flip the roast over halfway through if you're able.
Shred the beef in the slow cooker using 2 forks. Mix everything together and cook for another 30 minutes on LOW.
To serve, split open 1 hoagie rolls and stuff with beef. Top with ¼ cups giardiniera (or more to taste), and 2 slices provolone cheese if using. Repeat with the remaining ingredients and serve warm.
Notes
Nutritional information does not include cheese.
One 16-ounce jar of giardiniera has about 2 cups.
For a wet Italian beef, dip the cut side of the roll into the slow cooker juices before serving.
Store leftover beef with some of the cooking juices to keep it moist. Reheat gently in the juices before serving.