In a bowl separate the boiled egg white and egg yolk. Mashed d egg whites and add mayo, Also mashed the egg yolk, add diced onions and mayo mix well. In another bowl mashed avocado and add a pinch of salt mix well. Spread the egg whites mixture on the bread, cover with another layer of bread add d avocado mixture, cover with another layer of bread and add the egg yolk mixture and cover with another bread. Cut to your desired shape