How are wasabi nuts made?
I've used wasabi powder before and it always gets activated with water, not oil.

Searching about the industrial process, the closest I got was a comment in this cooking blog (emphasis mine):


  In the commercial world they add rice flour into the mix to make it all stick together, but before that they cook the peas and dry roast them or just dehydrate them. Once that is done then they use a "coating" machine which looks a bit like a cement mixer and slowly rotate the machine which contains the rice flour/wasabi mix.


So I think the key is: roast the nuts, use oil or arabic gum to make the surface of the nut sticky, cool it down to below 32ºC then add the wasabi powder mix. As long as it stays dry the wasabi powder won't get activated, which will happen only when you put them in your mouth.

I suppose the rice flour is to thin out the mix a bit, since pure wasabi powder might be too strong, to help coat the nuts uniformly and to keep moisture away which would kill the wasabi flavor.