Grass fed beef can be a little chewy. Actually it can be very chewy depending on the cut. One solution is to marinate the beef in soy sauce before cooking. Another is stewing the meat. That said if you want to make something like shish kabobs or London broil, you are going to need a marinade.
Now you can use meat tenderizers but the issue with most of those is that if you over marinate the meat it can become mushy and gross. Anything papaya or pineapple based can really break down the meat and not necessarily in a good way. Chewable is good. Edible without teeth is not.
MSG is also a popular “meat tenderizer”. I refuse to eat it because unfortunately, it is the secret to making normal rats obese. Yes, if you have two Sprague-Dawley rats and you feed one rat MSG and rat chow and the other rat just rat chow you will end up with one morbidly obese rat and one normal size rat. I don’t want to eat anything that is proven to make rats obese. Just sayin. I can get fat without any help.
Which brings me back to soy sauce or in the case of gluten-free eating, tamari. Soak a steak in tamari for 24 hours and you will end up with a reasonably tender piece of meat with all the flavor or grass fed and all the reachness and saltiness of soy sauce.
So here is my recipe for marinade
1/3 cup soy sauce
1 tsp garlic powder
2 TB rice wine vinegar
1 tsp dried rosemary
Mix all ingredients together in a plastic bag
Add meat and squeeze out any extra air in the bag.
Marinate meat overnight or at least 24 hours tuning at least once
Grill or otherwise fast cook to your heart’s content!
This is an all purpose marinade for beef. I would not use it on port or chicken, but on beef its quite basic and very good.