I bought a 1/4 grass finished cow (I had a good experience with a 1/2 pig from the same seller, so didnt feel the need to start small).
We cooked some ground beef, and it was fine. But the second cut we tried were the NY strips and the fat on them tasted strongly of fish. I prepared the steak as i would any other store bought steak. I salted then fried in a cast iron pan on high with a little oil, removing the steaks from the pan at 125F. This normally produces steaks I enjoy a lot.
Based on a little research, it is common for grass finished beef to have some odd flavors if you are used to grain finished beef (almost all beef is raised on grass, the difference is what they are fed in the end to fatten up).
So, if all my steaks did taste fishy, is there a preparation method to mitigate the fishiness?
I'm familiar with gamey flavors of meat, having eaten quite a lot of moose, caribou, rabbit and the parts of a cow most people don't seem interested in. This fishy flavor was not like those. The fat tasted like I had bitten into one of those fish oil pills, and it was only the fat that tasted this way, I separated it from the flesh to check.
Best Answer
Grass-fed (and finished) beef fat tastes fishy because it effectively is similar to fish oils. In particular, grass-fed beef fat is dramatically higher in omega-3 fatty acids (alpha-linolenic acids) as opposed to omega-6 (linoleic) fatty acids; this NIH funded study for example found:
Meaning that grass-fed beef might have a 3:2 ratio of o6:o3 fatty acids, while grain-fed beef has a 13:2 ratio - a ratio over 4 times higher.
Fish tends to have even more omega 3 fatty acids, tending to a ratio of less than 1 (so, more omega 3 than omega 6); so I wouldn't imagine your beef tastes entirely like fish. But you're definitely going to taste some 'fishiness' in there in grass-fed and grass-finished beef as compared to grain-finished or grain-fed.
As far as how to prepare it, the challenge with beef is the strong beef flavor that you don't want to entirely cover up (or you wouldn't be buying a nice grass-fed side of beef, you'd be buying something from the local megamart).
My suggestion is to take your cue from fish itself: specifically, from strong tasting fish, and fish that is commonly eaten in steak-like preparations.