Many Americans eat sushi, but quite a few don't know about toro, or fatty tuna. This is from the belly of the tuna and has a higher fat content than regular tuna, and is therefore much more tasty. The fattiest part is called "Otoro". It melts in your mouth like butter and is an experience approaching...well, use your imagination.
I have been eating toro for a while, but it wasn't until I was in Korea this week that I learned this: no matter how much wasabi you put on toro, it will not burn your mouth. I was told this by my Korean host (we were eating at a sushi restaurant), so I experimented. Sure enough, you can put enough wasabi on toro to choke a horse, but you won't taste it at all. The fat in the tuna neutralizes the spiciness, and all you taste is the buttery excellence of the tuna.