In slow cooker, add flank steak and sprinkle with oregano, crushed red pepper, and minced garlic. Pour tomato juice over top.
Cover and cook on low for 7-8 hours or on high for 3-4 hours.
Remove meat from slow cooker and shred meat. Return to slow cooker and cook in juices for additional 30 minutes. If desired, stir giardiniera into shredded meat to cook.
Cut Italian bread length wise and into 6 (or desired) number of sandwiches.
Take bottom piece of bread and top with shredded meat. Drizzle with cooking juices to just moisten the meat and bread. Top with more giardiniera and sprinkle with shredded cheese. Cover with top of Italian bread and serve immediately.
Giardiniera is an Italian hot or sweet pepper blend found in most major grocery stores.