Protect your surface by covering it with a sheet of newspaper, a paper towel, or a garbage bag.
Make sure hard-boiled eggs are completely cooled.
Stir food coloring into a cup of hot water. The more you add, the darker the color.
Mix in 1 tbsp of distilled white vinegar.
Carefully drop your hard-boiled egg into the cup and let it sit until it reaches your desired color (about 10 minutes).
Remove the egg from the cup with a spoon and let it dry completely.
