Bring broth to a boil in a large saucepan. Season broth with juice and zest of lemon or lime, fresh ginger, and minced or sliced garlic.
Add vegetables from firm to soft, starting with onions, carrots, celery, bok choy and mushrooms. Simmer gently until all vegetables are tender, about 10 minutes.
If serving protein separately, (beef, chicken, shrimp or tofu) cook and place in separate bowls. If not, feel free to add to the soup, cooking until meat is done.
5 minutes before serving add sliced snow peas, green onions and bean sprouts. Season to taste with sesame oil and fish sauce if desired.
Season to taste with sesame oil and fish sauce if desired. Serve soup in large bowls with condiments on the side so that each person can season to his or her liking.