We bought 1/2 grass-fed cow from a farm that we will never buy from again. It's hard to imagine such tough beef and such a bad butchering job, it's all cut and wrapped in 3 lb chunks, no hamburger, no steaks. The seller kept hedging on how long it had been aged. I'd say not more than 2-3 days. It must have been wild, and cattle prods used before killing by slicing it's neck. We've decided give all the left-overs to our dogs to help us get through this beef faster.
However we still must cook and eat it. The only process that works so far is this:
1. Thaw the meat overnight in aan aciddic marinade of vinegar or lemon juice or buttermilk or yogurt.
2. Beat it to death with a tenderizing mallett
3. Peirce it all over with a thin, pointed metal something
4. Put it back in the rinsed marinade bag with one of the naturally occuring enzymes: papain from papaya, bromelain from pineapple, or oractinidin from kiwifruit. To do this prepare the fruit, than beat it to pulp with the tenderizing mallett in a bowl and pour it all into the bag. Put it in the refigerator over night.
5. The next morning dry it and salt it, or put in in a brining salt solution.
6. Before cooking it that night, rinse the salt off and dry it.
7. Braise it first, then cook it slowly at low temps.
This does work. It becomes chewable and it's rather tasty. It's certainly nothing like a commercially fed beef.