Combine sugar cubes and water in saucepan and bring to boil, stirring or shaking pan occasionally until sugar melts. Cook without stirring until syrup reaches hard ball stage (225�F on candy thermometer). Whip egg whites to form soft peaks, then reduce speed of mixer and slowly add syrup. Beat in chocolate pieces (they will melt partially). Cool to lukewarm. Whip cream until stiff and fold into mousse. Chill for at least 4 hours. To serve, place Strawberry Sauce on chilled dessert plate (or in @tuile cup), then top with mousse. Garnish with 1 or 2 mint leaves and pass remaining sauce separately. Strawberry Sauce: Puree strawberries. Stir in remaining ingredients. Cover and chill thoroughly.