Add eggs into a small saucepan or pot and cover with water.
Bring to a boil over high heat. Once boiling, reduce the heat to minimum and cook for 7 minutes.
Drain the eggs and immediately rinse with cold water (to stop the cooking).
Gently tap all over the surface of the egg and peel off the egg shell. (Tip: I find it easier to do this under running cold water, or in an ice bath).
Repeat with the remaining egg.
Add the peeled eggs into a medium bowl.
Use a fork to mash the eggs.
Add kewpie mayonnaise, Dijon mustard, salt and pepper (to your taste), green onions and give it a mix to combine thoroughly.
Spread the egg salad mixture evenly onto a slice of white bread.
Add the second slice of bread on top and gently press down.
Slice in half and serve.
If you prefer, you can trim off the crusts prior to serving.