Simple Summer Vegetable Soup

1. * Wash and cut the fresh spinach into strips.
2. Melt the butter in a soup pot; add the onion, carrots and celery.
3. Cook over medium heat, stirring often, for 5 minutes.
4. Add the broth and tomatoes and simmer another 10 minutes.
5. Add the spinach and cook for an additional 1 minute.
6. Seasoni with salt and pepper to taste.