An ancient method of coloring eggs
The children can participate just fine. The outermost, dry layers of yellow onions are used. Then you "fold" these sheets around the egg.
To keep this in place, fold kitchen paper around it and finish with a rubber band. Then boil the eggs for at least 15 minutes. It's a little wonder to unpack the eggs again! Let the children participate in this too. If you want to highlight the absolutely lovely colours, you can add a little oil to the eggs. Good luck! (I don't usually eat the eggs, they're just for decoration with us, so I don't know if they taste like onions!)