Thank you for that FF. Beef is not on the menu for the next couple of days, but I'll pick some up to try for the weekend. I like the idea of adding the garlic. Glad to know it works with chicken also. Sally recommends marinating chicken with lemon juice, so I bet the lemon/ACV pretty much work the same.
Sally doesn't seem to marinate fish, but lots of good stuff added, not all but most use wild salmon. Lamb is not marinated either, but sometimes made into a stew with lots of good stuff.
BTW here is an article and some ideas for your remaining liver: