These Philly steak sandwiches are loaded with shredded beef, peppers, onions and cheese and served on toasted sourdough bread, rather than hoagie rolls. They're so delicious, you might think you've died and gone to Philadelphia!
In a large skillet, cook onion and garlic in hot oil over medium heat about 5 minutes or until tender. Add shredded beef, broth, pepperoncini peppers oregano, paprika, black pepper and celery seed. Bring to boiling; reduce heat. Simmer, uncovered, about 5 minutes or until heated through and liquid nearly evaporates.
Place cheese slices on half of the bread slices. Spread mayonnaise on remaining bread slices. Spoon meat mixture over cheese slices. Top with remaining bread slices.