1. Slice steak on the diagonal into very thin strips. (It slices more easily if partially frozen.)
2. In a bowl, combine the ginger, garlic, 1 teaspoon cornstarch, soy sauce and egg white. Add the meat and toss to coat. Set aside for 5 minutes.
3. In a large skillet or wok, heat oil on -medium-high; brown the meat. Remove the meat; set aside. Add the green pepper, onion, celery and 1/2 cup water; cover and cook over medium heat for 3 minutes.
4. Add ketchup and sugar; cover and cook for 2 minutes. In a small bowl, whisk the remaining cornstarch and water until smooth. Stir into beef mixture; return to skillet. Cook until liquid is slightly thickened. Add tomatoes and stir for 1 minute just until heated through. Serve with rice. Yield: 4 servings.