Add the following ingredients to a bowl: sugar and meringue powder. Starting on a low speed, mix well until no lumps remain.
Still on a low speed, pour in the water and keep mixing until completely combined. You should mix for around 5 minutes to achieve soft peaks.
If your icing seems too thin, just keep mixing. If it seems too thick, add a teaspoon of water and mix well.
Using a toothpick, add a small amount of black gel food coloring. Instead of using a stand mixer, use your hand instead. Add more black using your toothpick, until you reach the color you're looking for.
Notes
NOTE: If you want to make this icing with cocoa powder, make your white icing using the recipe above, and then add around 3 teaspoons of cocoa powder. Mix well and then add a toothpick sized amount of black food coloring to deepen the color.