1Preheat the oven to 325F.
2Cut the steaks across the grain into thick strips - about 1 1/2 inches wide. Put the flour into a shallow bowl and season it with salt and pepper. Heat a heavy pot on the stovetop with a generous drizzle of oil and brown the meat in batches on all sides, then transfer it to a plate.
3Add the onions, garlic and celery to the pot and cook for a few minutes, until starting to turn golden. Return the steak to the pot, add the tomatoes, stock, Worcestershire and steak spice (or whatever herbs and spices you like), cover and slide into the oven for 2-2 1/2 hours, until the meat is very tender.
4Serve over mashed potatoes or buttered noodles.