Hard boil your eggs.If you have a favorite method - go for it! If not, Bring water to boil in saucepan large enough for eggs and water. Gently add eggs to water and boil for 12 minutes. Drain eggs and cool them in an ice bath for 3 or 4 minutes. Peel them.
Place cooke eggs in medium sized bowl. Chop eggs with a pastry cutter. Easy Peasy! Alternately, you can chop on a cutting board and add to bowl.
Add mayo, celery and mustard to eggs and mix thoroughly.
Toast 8 slices Ketonia bread.
Divide egg salad between 4 slices of Ketonia bread. Top with remaining slices.
Enjoy a taste of your childhood! (but don't let it sit in your lunchbox till noon, cuz, ewww.)