Tarako: Some recipes call for "raw" or unpreserved tarako. The only raw roe available around here is shad roe, which may also be used in this dish but I have not tried. So I used the usual salted tarako. It is interesting that the saltiness of the tarako reduces to the saltiness of the simmering liquid when it is cooked. So I do think either raw or salted tarako will work in this dish. I first cut one side of the membrane along the long axis and then cut it in 1 inch segments. I like this way rather than keeping a roe sac intact while cooking and then slicing it when serving. The way I prepared it made the tarako "blossom" when cooked like you see here in the picture, since the sac membrane will contract and invert the roe. This, to me, is more presentable and gives a better texture.
When the seasoning liquid came to a simmer, I added the tarako and simmered it gently for 15 minutes and let it cool to room temperature in the simmering liquid (Picture below).
*This was developed by a Japanese seed company but is much more popular in the U.S than in Japan for some reason. If you are interested, here is a story about broccolini (in Japanese).