Beat Eggs In A Large Bowl. Add The Celery, Onion, Bean Sprouts, Mushrooms, Chicken, Beef, Pork, Salt And Pepper. Mix Together. Heat Oil In A Medium Skillet Or Wok And Brown Egg Mixture 1/2 Cup At A Time. When All Of The Mixture Is Browned, Set Aside. To Make Sauce: Dissolve The Bouillon In The Hot Water In A Small Saucepan; Add Sugar And Soy Sauce And Blend Well Over Medium Heat. Add Cold Water And Cornstarch And Stir Until Thick And Smooth. Serve With Egg Foo Yung.