In a wok or 12-inch skillet heat the 3 cups of peanut oil to 375 degrees F. Add the vermicelli to hot oil and cook about 8 seconds or until puffed, turning once. (Do not let brown.) Drain on paper towels; set aside. Cool and discard peanut oil.
Cut chicken into 1-inch pieces; set aside.
For sauce, in a small bowl combine chicken broth, teriyaki sauce, and cornstarch; set aside.
Add 1 tablespoon cooking oil to the same wok or a 12-inch skillet. Preheat over medium-high heat (add more oil if necessary during cooking). Stir-fry lemongrass or lemon peel and garlic in hot oil for 15 seconds. Add the broccoli and cauliflower; stir-fry for 2 minutes. Add the mushrooms, red or green sweet pepper, and green onions; stir-fry for 1-1/2 to 2 minutes more or until vegetables are crisp-tender. Remove vegetables from wok. Add chicken to wok; stir-fry about 4 minutes or until no longer pink. Push chicken from center of wok.
Stir sauce; add to center of wok. Cook and stir until thickened and bubbly. Return cooked vegetables to wok. Add tomatoes. Stir to coat. Cook and stir about 2 minutes more or until heated through. Serve immediately with vermicelli. Sprinkle with cilantro or parsley, if desired. Makes 4 servings.