In small saucepan, mix eggs with sugar, orange juice and vinegar. Cook, stirring constantly, until mixture thickens. Remove from heat and stir in butter and salt. Cool; then, fold in sour cream. Chill while preparing fruits. Combine fruits and marshmallow. Fold in creamy dressing; spoon carefully into serving bowl. Chill 24 hours to allow fruits and dressing flavors to blend fully. Garnish with fruits and sprigs of mint if desired.