Add carrots, celery, tomatoes, green beans, potatoes, tomato paste, broth, water, bay leaf, oregano, thyme, red pepper flakes, ½ teaspoon salt, and ¼ teaspoon pepper. Bring to a boil. Reduce heat to low, cover, and simmer until potatoes are tender (approximately 15-20 minutes). Remove from heat; stir in parsley. Season with additional salt and pepper, if necessary. Remove bay leaf before serving.