Preheat oven to 300 degrees.
Heat olive oil in a large Dutch oven over medium-high heat. Season chuck roast evenly with salt, pepper and flour. Sear roast for 5 minutes on each side. Remove to a plate.
Add one cup of the sliced onions to the Dutch oven. Cook for 3-4 minutes until slightly soft and translucent. Deglaze the pan with the red wine, scraping up any brown bits from the bottom of the pan. Place the roast back into the pan and add the beef broth, worcestershire sauce and bay leaf. Bring to a boil, Cover and place in the oven to cook for 2 1/2- 3 hours or until tender enough to shred with two forks. (Mine took 2 1/2 hours.)
In a large skillet over medium-high heat, melt butter, Add remaining 3 cups onions and 3 cups green peppers. Cook until softened and lightly browned, about 9-10 minutes. Remove from heat. Place onions and peppers in a bowl, Set aside until you're ready to assemble sandwiches.
Remove the roast from the oven. Remove the meat from the broth. Shred the meat with two forks. Strain the broth, skimming off the fat. Add some of the gravy to the shredded meat and save the extra for serving on the side in small bowls.
Slice kaiser rolls and place bottom of rolls on a rimmed baking sheet. Top the bottom half of each roll with one slice of cheese. Then top evenly with a generous helping of the shredded beef. Top each evenly with peppers and onions and then two more slices of cheese per sandwich along with kaiser roll top. Place in oven for 4-5 minutes just until cheese just begins to melt. Serve with extra gravy on the side.