In large bowl, mix together soy sauce and cornstarch. Add meat and toss to coat. Let meat marinate for 30 minutes.
In a large wok (or dutch oven), brown meat quickly in 1/4 cup Peanut oil until it loses its red color. Remove from pan; set aside; and discard extra oil.
Add remaining 1/4 cup of oil and saute ginger root and garlic over high heat. Add broccoli to pan (stirring constantly) and cook until just tender. Blend in oyster sauce, sherry, red pepper and sesame oil and cook 1-2 minutes longer.
Add water chestnuts and reserved meat; mix so that everything is blended.