Makes: 6 servings at $2.50 each. Prep: 20 minutes. Refrigerate: 2 hours or overnight. Roast: at 425° for 25 minutes. Broil: 15 minutes.
Mix garlic, salt, pepper, pepper flakes, Parmesan, parsley, oil and seasoning in bowl to form paste.
Lay steak on work surface. Holding sharp knife parallel to work surface and starting at long side, slice flank steak in half to opposite long side, without cutting all the way through; open up steak like a book.
Rub steak all over on both sides with seasoning paste. Arrange slices of provolone over surface of steak, leaving 1-inch border all around edge. Top with roasted peppers. Starting at short end, roll up steak to enclose filling. Tie roll at 1-inch intervals with kitchen twine. Wrap in plastic wrap. Refrigerate for 2 hours or overnight.
Heat oven to 425°F. Remove plastic wrap from steak. Let meat stand at room temperature while oven is heating, but no more than 30 minutes. Place steak on broiler-pan rack in broiler pan. Arrange onion quarters around meat on rack.
Roast the beef and onions in 425°F oven for 25 minutes. Turn on oven broiler. Broil steak and onions 4 inches from heat for 15 minutes, turning once, or until internal temperature of meat registers 150°F. Let stand 15 minutes. Remove twine. Slice crosswise.