fong-konged!

At first glance the blob photographed above looks very much like something the Jolly Green Giant would expectorate.
It is in fact Wasabi, or what I thought was Wasabi. But let's have a little lesson before we get into that.
Wasabi japonica aka Japanese Horseradish aka sneaky-bastard-stuff-that'll-make-your-nasal-passages-feel-like-
they've-been-rinsed-through-with-battery-acid, is a regular accompaniment to sushi. Apparently, the condiment has certain anti-microbial properties, pretty handy I'd say, when you're chugging back raw fish (is there Japanese etiquette for vomiting politely from the food poisoning?)
I say it's sneaky because at first taste, the unassuming stuff lays a bit of sweet on your tongue before it proceeds to puncture your sinuses with a million hot needles. And once you get pass the sensation of your brain being pulled out of your skull by the crown, you'll be reaching for just a little more. It's potent, wicked, addictive stuff.
Now that's what I thought I was shnarfing. Wasabi.
Not so, according to a plethora of online sources. Genuine wasabi is difficult and expensive to cultivate. So much so, that only a small percentage of sushi-ya in Japan actually serve it. The green blobs we've become accustomed to are usually a mash of ordinary horseradish, mustard and green food colouring.
The real makoya is a greenish root that's chopped into little bits with a fine-toothed grater. According to this site, aficionados say, "The taste of genuine wasabi is like a warm explosion that quickly fades away to a slightly sweet afternote."

Knowledge can be something of a party-pooper.