Best-Ever Swiss Steak

Preheat oven to 325°. Place steak between 2 pieces of plastic wrap and pound with a meat mallet until 1/2" thick.  Heat 2 tablespoons vegetable oil in a medium dutch oven over medium high heat. Add onions and garlic and cook until softened and beginning to brown, about 5 minutes. Remove from pot and set aside. Season meat on both sides with salt and pepper and then dredge meat in flour. Add remaining 2 tablespoons oil to pot and sear steak until deeply golden on both sides. Meanwhile, in a medium bowl, mix together tomatoes, water, oregano, and Worcestershire, then season with salt and pepper. Pour over seared meat and sprinkle onion mixture on top.  Cover pot and bake for 2 to 2 1/2 hours, until meat is falling apart. Sprinkle with parsley and serve.