In a large soup pot, combine the vegetable broth, onions, carrots, celery, garlic, salt, dill, and fennel. Bring to a boil, then reduce the heat, cover, and simmer gently for about 5 minutes.
Stir in the tomatoes and their juice. Add the bulgur and mix well. Return to a boil and simmer, covered, for another 15 minutes, or until the bulgur is tender, stirring occasionally. Add pepper to taste.