Heat a large pot or Dutch oven over medium heat; cook and stir beef and Italian dressing in the hot pot until meat is evenly browned, about 5 minutes. Stir in 2 cups water, diced tomatoes, broth, tomato sauce, bouillon, bay leaf, garlic, oregano, salt, and pepper; bring to a boil. Reduce heat to medium-low, cover, and simmer until meat is tender, about 1 1/2 hours.

Add potatoes, carrots, bell pepper, and onion to the pot; cover and continue to simmer until vegetables are tender, about 45 minutes.

Combine flour and 3 tablespoons cold water in a small bowl; mix until smooth. Stir into stew and bring to a boil; cook and stir until thickened, about 2 minutes. Discard bay leaf before serving.