I have never tried with a milk solution but that sounds amazing; i do always make it with onions though.
I have never tried cow's toungue but I would NOT be opposed to it! I have a friend who loves it, as well as pig ear (not together though LOL)
I love pickled and vinegar anything as well, like you mentioned; my friends were shocked when i told them I always add a bit of vinegar to lentil stew after its done and served in the plate and they were shocked when I told them to add a bit of vinegar and sugar to strawberries (sounds strange, I know, but it makes it even sweeter).
Also, sort of related to bone marrow, cartilage in general. Some people get grossed out but it's so good.
Here's how my dad taught me to make it:
Take the liver you get, pat it dry with a paper towel, and put it in a bowl of milk, seasoned with salt/pepper powder/onion powder/paprika
Let it sit overnight covered in the fridge. Next day, drain off the milk (we usually gave it to the animals), pat it dry, dip it in an egg wash mixture, bread it in panko (seasoned the same way as the milk, you wanna be decently heavy on the seasoning)
Ripping hot skillet with some oil at the bottom, fry it until golden on either side (and do cut it open to see if it's cooked all the way through, not sure on time measurements here, this is how I figure it out.)
He always makes a shit ton of caramelized onions about an hour or two before he's ready to cook the liver. Best for this is vidalia onions in my opinion. But use whatever, a mix of onions is also delicious.
Also, if you like mushrooms, I'd suggest sautéing up some mushrooms in butter as well to plate with it. Small amount of butter, let it melt, throw the mushrooms in, seer 'em until the water is gone, throw in a bit of garlic, season with salt/pepper/Worcestershire sauce
Voila, you get Mr. Foster's Pennsylvanian Dutch Staple Lunch. Best served with a simple baked potato on the side if you need some more filling on the plate. (Dad puts sour cream on top of his baked potatoes. Makes 'em really creamy.)
Also yeah nah that's something my mum does for her strawberries when she makes strawberry shortcake. She learned a lot from my Oma (dad's mum.) Vinegar does a lot to make stuff super sweet cause of the chemical reactions it causes. Totally in agreement on marrow and cartilage though. Pigs ear is great and tastes amazing with mustard. I treat it like I treat any Germanic/Slavic food that I grew up with. Best served with mustard and sauerkraut. Cannot go wrong with the holy trio of pork/mustard/sauerkraut. The Germans got it down to a science.
