ELI5 Wasabi - is most wasabi really “fake” outside of Japan?

What exactly is that sensation we feel with wasabi? Is it the same as the heat from chili peppers? Why does it go straight to the nose? How does it differ from similar foods like mustard and horseradish? Is wasabi outside Japan really fake? How do you tell if it’s real? Why is it paired with sushi? ... we explain like I'm five Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: stuthulhu, followups, suffaluffapussycat, jeffboyardean, infinity__now, reese_tora, abaday789 and mike_zzzzz To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Send us an e-mail: [email protected]