Begin by tenderizing the round steak with a meat mallet. In a shallow dish, combine the flour, salt, and black pepper. Dredge each piece of steak in the flour mixture, shaking off any excess.

In a large skillet, heat the vegetable oil over medium-high heat. Add the floured steak pieces and brown them on both sides, about 4-5 minutes per side. Remove the steak from the skillet and set aside.

In the same skillet, add the sliced onion and green bell pepper. Sauté for about 3-4 minutes until they are softened. Add the minced garlic and cook for an additional minute.

Return the browned steak to the skillet. Pour in the diced tomatoes (with their juice), beef broth, Worcestershire sauce, oregano, and thyme. Bring the mixture to a simmer.

Reduce the heat to low, cover the skillet, and let it cook for about 1.5 to 2 hours, or until the steak is tender. Stir occasionally and add more broth if needed to keep the sauce from drying out.

Once the steak is tender, taste the sauce and adjust seasoning if necessary. Serve hot over mashed potatoes or rice.