Mentaiko is made of Pollock roe, the eggs of the Alaska Pollock, which are used commonly in Japanese, Korean, and Russian dishes. I’ve always thought is was a Japanese food, however it originated from Korea, called myeongnan. It was introduced to Japan in the 1950s, where it became mentaiko, or karashi-mentaiko (spicy mentaiko). The roe is seasoned and marinated with chilli and spices; usually the redder it is, the spicier it is!
A popular variation in Japan is tarako, which is salted Pollock roe. In Japan it’s enjoyed with steamed rice and miso soup; my personal favourite. It’s also enjoyed inside onigiri (rice balls), sushi, and tempura, and pasta.
Other fish eggs used in Japanese cuisine are:
Tobiko – Flying fish roe. These eggs are very small, no bigger than a millimetre. They have a sweet-salty taste, and have a crunch texture. They’re commonly used as decoration on sushi.
Masago – Smelt roe. This is often mistaken as tobiko due to their visual similarities, however masago is slightly smaller and slightly bitter. It’s often used as a substitute for decoration as it’s cheaper than tobiko.
Ikura – Salmon roe. These eggs are bigger than tobiko, and more squishy and gooey in texture, and are eaten with sushi and sashimi.
I’ve eaten mentaiko since I was a child, and one of my daughters also loves it (my other children aren’t as enthusiastic) I’ve haven’t met many Western people who like the taste or texture, but I suggest giving it a go!