4 tablespoons olive oil, divided
1 boneless beef chuck eye or other boneless beef chuck roast (4 to 5 pounds)
2-1/4 teaspoons salt, divided
2-1/4 teaspoons pepper, divided
2 small onions, coarsely chopped
9 garlic cloves, chopped
3/4 cup dry red wine
4 cups beef stock
3 fresh thyme sprigs
4 teaspoons Italian seasoning
1-1/2 teaspoons crushed red pepper flakes
4 medium green peppers, cut into 1/2-inch strips
1 teaspoon garlic powder
12 crusty submarine buns or hoagie buns, split partway
12 slices provolone or part-skim mozzarella cheese
Giardiniera, optional
In a 6-qt. stockpot, heat 3 tablespoons oil over medium-high heat; brown roast on all sides. Sprinkle with 2 teaspoons each salt and pepper. Transfer to a 6-qt. slow cooker.
Add onions to stockpot; cook and stir until lightly browned, 2-3 minutes. Add garlic; cook 30 seconds longer. Add wine; cook 3-5 minutes, stirring to loosen browned bits from pan. Stir in stock, thyme, Italian seasoning and pepper flakes; transfer to slow cooker. Cook, covered, on low until beef is tender, 7-9 hours.
About 1/2 hour before serving, preheat oven to 350°. Place peppers in a 15x10x1-in. baking pan. Drizzle with remaining 1 tablespoon oil. Sprinkle with garlic powder and the remaining 1/4 teaspoon salt and pepper; toss to coat. Roast until peppers are softened, 15-20 minutes, stirring halfway.
Remove roast; cool slightly. Strain cooking juices into a small saucepan, reserving strained mixture and removing thyme stems. Skim fat from juices; heat through and keep warm. Coarsely shred beef with 2 forks; stir in reserved strained mixture. If desired, moisten beef with some of the cooking juices.
To serve, preheat broiler. Arrange buns on baking sheets, cut sides up. Broil 3-4 inches from heat until lightly toasted. Remove from oven; top each bun with 2/3 cup beef mixture and 1 slice cheese. Broil until cheese is melted, about 30 seconds.
Top with peppers and, if desired, giardiniera. Serve with cooking juices for dipping.