The only thing I would be concerned about is - is the liver organic or feild raised? I think liver is probably pretty nutritional, but if the meat is conventionally raised, I wouldn't use it. The liver processes a lot of crap we get in our environment and if the animal has been exposed to unhealthy practices, it will be "contaminated".
Oh I wouldn't have even bought it if it wasn't good. It's from my milk supplier and it's her personal stash. I mentioned that I was saving money to order a small amount online and she let me go in her freezer and pick out a few things.
Thanks for the suggestion I'll go over to Kellymom.
The 14 days frozen thing is to kill possible parasites, so I can't imagine that thawing a little and refreezing would be a problem if the ilver had already been frozen 14 days before it was refrozen. I use a fine microplane grater for my frozen liver, but any fine grater would work. As to how much, an egg yolk isn't very big, so maybe a 1/4 teaspoon?