In the same pot, add the onions, celery, carrots, garlic, and basil. Sauté for about 5 minutes until vegetables are soft. Stir in the browned beef and flour, stirring to coat the meat. Cook for 1 minute. Stir in the broth, milk, tomatoes, and potatoes. Bring to boil, turn heat to simmer, cover, and cook for about 30 minutes, until potatoes are tender.