In a large Dutch oven or pan, heat the olive oil over medium heat. Add half of the beef in a single layer without crowding. Cook undisturbed, for about 5 minutes, lowering the heat if the pan starts to smoke. Toss the beef around to brown the other side for another couple of minutes. When well browned, remove from the pan and repeat with the remaining beef.

Preheat your oven to 325 degrees F.

Set the browned beef aside for the moment and add the butter to the now empty pan. Add the onions and cook over medium heat, stirring occasionally for about 10 minutes. Add the carrots, celery, and garlic and cook for another five minutes. If things start to stick to the pan, toss in a little more butter or oil.

Sprinkle the vegetables with a teaspoon of salt and the flour. Stir to coat. Pour the stout and tomatoes into the pan, along with the beef and bay leaves. Stir and allow to come to a simmer.

Turn off the heat and arrange the potato slices over the top of the stew. Sprinkle the remaining salt and the thyme, along with a quick drizzle of olive oil, over the top. Put the cover on the pan and place in the oven to bake for one hour.

Increase the oven temperature to 425 degrees F. Remove the cover from the pan and cook for another 30 minutes. Serve hot.