Grass only meat is leaner and more flavourful than grain fed (or grain finished) meat. That means it can come out tough unless you follow a few principles.
Thaw to room temperature in your refrigerator, in cold water, or on the counter -- never in the microwave.
2. Maximize Moisture
Sear or brown the meat before cooking to lock in the juices.
Use a meat thermometer instead of making cuts to check doneness -- those little cuts release precious juices.
3. Lower Temperature and Shorten Time
Generally grass only beef needs about 30% less cooking time AND should be cooked at about 50 F less than most recipes indicate.
Enjoy rare or medium-rare: target an internal temperature between 120 F and 125 F. If you are cooking for someone who is immunocompromised then target the 145 F Canada Beef recommends for medium-rare just to be safe.
If you like your meat well done then you MUST cook grass only beef with moisture so it will not come out tough: braise or stew it.
4. Watch It
Grass only beef cooks quickly and can go from perfect to overdone in less than a minute.
Remove the meat when it is about 10 F below your target temperature: The heat will work its way through the meat over the next 8 to 10- minutes as you let it rest before carving.