Remove the membranes from the tarako ahead of time. It's delicious with a lot.
Cook half of the egg mixture, and when it's slight just slightly uncooked on top, put the tarako on top. (I placed them closer toward my side).
Roll it up, add in the rest of the egg mixture, cook it also and roll it up. An okonomiyaki spatula is easiest to use.
It's not best with mentaiko as the tamagoyaki becomes too spicy.
"Fish Sausage Good for a Bento" [Fish Sausage Piccata]
For all kinds of bento: "Cooked Tarako"and "Striped Seaweed Bento".