Using a medium size heat safe bowl, stir together the orange flavored gelatin and boiling water. Stir until the gelatin is completely dissolved.
Stir in the cold water. Place in the refrigerator for 15 minutes.
Remove the cooled gelatin from the refrigerator, and whisk in the vanilla instant pudding until completely incorporated. Cover the bowl and return to the refrigerator for 20 minutes.
Remove the bowl from the refrigerator. Fold in the whipped topping, drained mandarin oranges and mini marshmallows. Cover and return to the refrigerator and chill for 2 hours or overnight.
Just before serving, garnish with the reserved mandarin oranges and mini marshmallows.
Notes
This salad can be made a day ahead of time for better flavor.
Feel free to experiment with different fruits or toppings to customize your salad.