Preheat oven to 350.
Lightly grease a doughnut pan.
In a medium-sized bowl combine flour, salt, baking powder, sugar, and cocoa powder; set aside.
In a small mixing bowl combine egg, vanilla, milk and sour cream; beat on low just until incorporated.
Slowly add the flour mixture to the milk mixture and mix with a spoon just until combined; don't overmix.
Pour the batter into a piping bag with a wide tip and pipe into doughnut holes.
Bake for 8 to 10 minutes, or until the top of the doughnut springs back when touched.
Remove from oven and let cool for two minutes, before inverting onto a cooling rack. Let cool.
In the meantime prepare the shredded coconut with the food color, if using.
Put the shredded coconut in a ziploc bag, add 3 drops of food color in the ziploc bag, seal it, and work it with your fingers until completely colored.
Spread Marshmallow Fluff on top of doughnut and top with shredded coconut.
Best when eaten same day.