Stir-Fried Pork Soup

Ingredients:
2/3 lb boneless pork loin, cut into thin strips
1 cup sliced fresh mushrooms
1 cup chopped celery
1/2 cup diced carrot
2 tablespoons vegetable oil
6 cups chicken broth
1/2 cup chopped fresh spinach
2 tablespoons cornstarch
3 tablespoons cold water
1 egg, lightly beaten
pepper

Directions:
In a 3 quart saucepan, stir-fry pork, mushrooms, celery and carrots in oil until pork is no longer pink and vegetables are tender.
Add broth and spinach.
Combine cornstarch and water to make a thin paste; stir into soup. Return to a boil; boil for 1 minute.
Quickly stir in egg. Add pepper.
Serve immediately.