Prepare the beef by cutting it into large pieces and dusting with flour.
Heat oil in a large skillet over medium-high heat.
Sear the beef pieces on all sides until browned, about 4-5 minutes per side.
Remove the beef from the skillet and set aside; add chopped onions, garlic, carrots, and celery.
Cook the vegetables for about 5 minutes until softened.
Stir in the diced tomatoes and Worcestershire sauce.
Return the beef to the skillet and add the beef broth.
Bring to a simmer, cover, and reduce heat to low; cook for 1.5 to 2 hours.
Check the seasoning, adding salt and pepper as needed before serving.
Serve the Swiss steak hot, paired with mashed potatoes or rice.