Beat eggs & stir in water. Mince scallions. Blend cornstarch and remaining cold water to a paste. Bring stock to a boil. Reduce heat to medium and stir in sugar, salt, sherry & soy sauce. Add cornstarch paste & cook, stirring, until soup thickens & is smooth. Reduce heat to low. Pour eggs in slowly, stirring constantly, until they separate into shreds; then turn off heat. Garnish with minced scallions. Serves 4-5.