In a small bowl, beat egg with water. Melt butter in a large skillet over medium low heat. Add egg and leave flat for 1 to 2 minutes. Remove from skillet and cut into shreds.
Heat oil in same skillet; add onion and saute until soft. Then add rice, soy sauce, pepper and chicken. Stir fry together for about 5 minutes, then stir in egg. Serve hot.