White Fish Soup

Heat oil in a soup pot over medium heat. Add onion, bell pepper, and celery and cook until wilted, about 5 minutes. Add tomatoes and broth and bring to a simmer, about 5 minutes. Cook 15 to 20 minutes. Add cod, parsley, and red pepper flakes and simmer until fish flakes easily with a fork, 8 to 10 minutes more. Season with salt and black pepper.