Cut open the mentaiko and extract the contents.

Mix the mentaiko, mayonnaise, and pepper in a bowl to create the mentaiko mayo sauce.

In a separate bowl, beat the eggs gently to break the whites, then mix in the milk to create the egg mixture.

Heat half of the salad oil in a frying pan over high heat, then cool the pan briefly on a damp cloth before placing it back on medium heat. Pour half of the egg mixture into the pan.