In large saucepan, combine sugar, cornstarch, and gelatine; add water and lemon or lime juice. Over medium heat, cook and stir until slightly thickened; stir in a few drops of food coloring in color of juice used, if desired (yellow or green). Cool. Chill until partially set, about 1 hour, stirring occasionally. In small mixer bowl, beat egg whites until stiff but not dry; fold into juice mixture. In small mixer bowl, beat whipping cream until stiff peaks form; fold into juice mixture. Tape or tie 3-inch waxed paper or foil "collar" securely around rim of 1-qt souffle dish. Pour mixture into dish. Freeze 6 hours or overnight. Remove "collar". Garnish with whipped cream, candy lemon drops and gum drop slivers if desired. Return leftovers to freezer. Tip: Souffle can be chilled in refrigerato 6 hours instead of being frozen.