My husband likes mentaiko (salted roe) on his rice, with pickles, and an ONSEN TAMAGO (Hot Springs Poached Egg). Over the years we started a toast version. Onsen Tamago are made by lowering eggs in bamboo baskets into the Hot Springs waters which very slowly poach the eggs. If you have the Momofuku Cookbook by David Chang and Peter Meehan, look for the Slow-Poached Eggs recipe. Their version is very close to the real thing. The photo is a real Onsen Tamago with mentaiko (spicy version of tarako) on the Japanese favorite toast--extremely thick, toasted so crusty on the outside, and soft and fluffy on the inside. I prefer a firmer, healthier bread, but be sure to cut it thick. —BoulderGalinTokyo
1 x as many as you want
1/2 sac Mentaiko or Tarako salted roe, or 1/3 sac Bottagra
thick slice bread, (twice the thickness of a sandwich bread slice)
Remove the mentaiko sac-skin. Put it on the side if you want to eat it, or else throw it away. Put half the mentaiko into a small bowl. Add the onion and cucumber. Mix together.
If using Bottagra, use a microplane grater to separate the eggs or If chopping with a knife, mince very finely. Add 2/3 of Bottagra to the cucmbers and onions.
Toast the bread, slightly darker than medium.
Poach the egg. Learn from Amanda (and many other great tips too):
Place the hot toast on a plate and spread the cucumber onion mixture on the bread. If eating the mentaiko sac, put in the center. Place poached egg on the toast trying not to break the yolk (but if it breaks on the toast -not a disaster). Add the leftover mentaiko around the egg.
Or sprinkle the remaining 1/3 of Bottagra over the egg.
My cooking is low sodium-- we find the mentaiko is salty enough for us. If you need more, add a drop or two of soy sauce (not a drizzle).
NOTES: I always use the raw onion because I like it, but spring onions or scallions are fine too. You can replace the cucumber with (non-vinegary) radish, turnip, or cucumber pickles.