I don't know what happened on your end over the holidays, but over here not a lot of self-control was exercised. So, at least this week, I'm eating lighter than usual to make up for the craziness of the last few weeks. But I'm far from depriving myself of delicious things, though. This mushroom laab (or lap, most often spelled "larb") you're looking at right here? Not exactly deprivation.
Shimeji mushrooms are blanched quickly in simmering water then dressed with fish sauce and lime juice. Dried chili powder adds some heat. Then we have that important laab ingredient that gives the dish that smoky, "nutty" taste and aroma: toasted rice powder. You cannot leave that out. (I mean, you can. But then you can't call it a laab.)
That's pretty much how you make a simple laab that is more popular in the central plains of Thailand than the northeastern plateau whence it comes. When I make laab with ground pork or chicken (which is the version which North Americans are most familiar with), I do it the exact same way.
The only thing I do differently for this mushroom laab is leaving out the usual fresh mint leaves and opting for the earthier, more subdued culantro (also known as "sawtooth coriander" for its serrated edges). The result is a mushroom salad that's good enough to eat all by itself. But if you intend to eat it with rice (or sticky rice), seasoning it a little more intensely is all you have to do.