Slice chicken breasts into bite-sized pieces.

In a bowl, marinate chicken with salt, pepper, cornstarch, sherry, and egg for 30 minutes.

Heat a wok over high heat until very hot and dry.

Add vegetable oil to the wok.

When the oil is just beginning to smoke, add marinated chicken, and water chestnuts.

Stir-fry for 1 to 2 minutes, until chicken is mostly cooked.

Drain the chicken and vegetables through a colander or sieve, reserving 2 to 3 tablespoons of the oil.

Return the reserved oil to the wok.

Add the sauce ingredients (if any, based on external recipe) and cook for 1 to 2 minutes, or until the sauce thickens slightly.

Add the cashews, chicken, and vegetables to the wok.

Stir everything together until well coated with the sauce and heated through.

Serve immediately.