Spread the rectangular non-stick pan with cooking oil, add the egg mixture, after the eggs are slightly cooked on the bottom, with the top still half cooked, roll the egg to the bottom edge then slide it to the top side. Pour again egg mixture into the empty part of the pan. Repeat the rolling process until the eggs reach the desired thickness.
Spread one side of the bread with 1 tbsp KEWPIE MAYONNAISE ORIGINAL. Repeat on the other side of the loaf. Arrange tamagoyaki on the bread that has been smeared with mayonnaise, add baby cos lettuce on top of it, cover with another loaf. Cut diagonally into two. Serve.