Roast beef sandwiches served with horseradish cream has been served for years in many places. As far as straight grated horseradish I think it would be to strong, but to each his own.
FIRST AND ONLY TIME i SAW IT WAS IN A BACKYARD OF A RESTAURANT IN PUERTO RICO . Guy took regular 5 lb. can of paprika put it in a pot wet it down, let it dry a bit then put it in a cheesecloth like sack and tied it up...
Thats what I do I am 70 and have been doing it for 50 years I tried to fully retire 3 times, just could not sit still. Now I just had nerve and neck surgery so I may have to stop. Do what ever you want to do you have earned it. EJB
AMONIA Equals Bad, not fit for human consumption. Most likely it was thawed and left out then refrozen. I would go back to fish monger and complain. The fact that you say it was slighty frozen means it was not your fault it came like...