Here's the marinade we use for Grass Fed steak. We marinate sirloin, ribs, or the round steak.
Our Basic Marinade Recipe:
1/2 Cup of Olive oil
Garlic clove (wipe the steak with it.)
1 tsp. salt (we usually add this last, right before cooking)
1 tsp. pepper
1/2 tsp. mustard
1 tsp. honey
This is our basic recipe but make your own variations, and play with it.
Some like to add acid like 1 Cup Red wine Vinegar or Balsamic Vinegar. The acid will tenderize the meat. There are certain types of acid you can use: vinegar, lime or lemon.
Best to place your steak in the marinade overnight.