I got my hands on my first piece of grassfed cow liver the other day. The first thing I noticed was the liver was much thinner/flatter looking than the usual fluffy corn fed liver. I cooked it my usual way, in a skillet with onions. Tasting it, I found it rather dry and dense and with a less strong flavor than the cornfed. THe grassfed was also not creamy textured like the cornfed. I hate to say it, but it just wasn't as tasty as a cornfed liver. I have found that many grassfed items taste better to me than cornfed, but that was not the case with this liver. I am sure it was much healthier though and part of it may just be that I need to change my cooking style. Any advice on cooking these livers or changes that might improve the outcome of cooking grassfed meats in general?
Sounds like you cooked it too hot. As JohnnyR said, cooking liver on low heat is paramount. You might also want to try this: Cook your onions in a pan and when done, just put the pieces of liver on top of them. The heat permeating through the "bed" of onions will suffice to cook the liver. From my experience, grass-fed liver should have a lot more taste than corn-fed and better texture as well.
Most cornfed cows are probably suffering from some type of nonalcoholic fatty liver disease. Not quite good for the cow's health, but tasty for us. A similar process can be seen in the deliberate force-feeding of geese or ducks when producing foie gras. I guess if you want flavor over paleo principles, at least in this instance, you might want to buy cornfed beef liver in the future. If not, then how about eating it raw or blue rare?
I cook my grassfed liver on low heat in a frying pan while basting it occassionally with olive oil. You could try putting a little water in the pan and covering it towards the end of it's cooking time, this would help tenderize it and release some flavor. I have tried these techniques with my grass-fed liver and it turns out creamy and tasty every time.
A Jimmy Moore podcast on grassfed cooking may be of interest:
Stanley Fishman Shows How To Cook Grassfed Meats The RIGHT Way! (Episode 342) http://www.thelivinlowcarbshow.com/shownotes/1693/stanley-fishman-cooks-grassfed-meats-the-right-way-ep-342/
And here's Fishman's site: http://www.tendergrassfedmeat.com/
It could be an sample-of-one problem. It might have been badly treated or from a not-quite-healthy cow. The next one you get might be the best one you've ever had.
I talked to my dad about liver a couple weeks ago. He says that his father knew how to cut it properly so that it was tender and thin enough so that it could cook through before it got tough.
Grass fed liver makes great jerky for dogs. Cut it in chunks and boil it for a minute in water with some garlic and then add it to your dehydrator (if you have one) and dry it for about 5 hours until pliable and chewy.