In medium saucepan, combine amount of water specified on both rice packages (about 2 1/2 cups water); omit margarine and salt. Bring to a boil. Stir in brown and wild rice. Reduce heat; cover and simmer 5 minutes. Remove from heat; let stand, covered, for 5 minutes.
Meanwhile, spray large nonstick skillet with nonstick cooking spray. Add egg product; cook over medium-low heat, without stirring, until top is no longer wet. Do not turn. Remove egg from skillet; cut into thin strips. Set aside.
Heat oil in same skillet or nonstick wok over high heat until hot. Add celery, bell pepper and water chestnuts; cook and stir 2 minutes. Stir in peas; cook and stir an additional 2 minutes. Add cooked rice; toss lightly to combine. Add soy sauce; toss and cook until thoroughly heated. Sprinkle with pepper.
To serve, fluff rice with fork. Place rice and vegetable mixture on serving platter; sprinkle with egg strips and onions. If desired, serve with additional soy sauce.