I've seen quite a few posts on cooking Mergansers on this forum, so I figured I'd chip in with my technique for making a razorbill edible. I try to never shoot them, but the other day I got one by accident. (Last 5 minutes of shooting light, 3 ducks coming into the dekes head on, dark head, light body, orange feet, BOOM oh crap that wasn't a mallard!
Anyway, after gutting (this will smell terrible, honestly smells like gutting a fish) the key is to completely skin the body, I didn't even bother to pluck mine. Then clean off all of the fat, and any sinew, etc. because that's where all of the fishy taste comes from. I then breasted it out and took off the legs, you can bone the legs if you like but I kept mine whole. The boned meat shouldn't smell like fish at all, in fact it smells just like any other duck, maybe depending on what your merg has been eating. Then I made a simple brine with salt and red wine vinegar, you want to let the duck soak in the brine for at least 24 hours, but not more than that or it will start to pickle and will become tough. Take the duck out of the brine, wash it off, and then soak in buttermilk for at least 48 hours. Then it's ready to cook, I sauteed the breasts whole and then cut them into strips. Tastes really similar to venison, just remember to treat it like beef and you should be OK. Prepared this way it would also be good in a stirfry, satay sauce, curry, etc. Just don't do it too often because mergs can collect mercury due to their fishy diet, but if you're like me and can't bear to waste meat then this will get you an edible razorbill!