Season the steak with Montreal steak seasoning, salt, and pepper. Let it marinate for at least 30 minutes before cooking.
In a bowl, mix the softened butter with the thyme, parsley, and rosemary. Place the butter on a piece of plastic wrap and shape it into a small log. Twist the ends closed and place it in the freezer until firm.
Sear the steak for 1 to 2 minutes per side on the barbecue or in a skillet.
Then transfer the steak to the oven or to the upper rack of the barbecue and cook for an additional 4 minutes.
Remove the herb butter from the freezer and slice it into small rounds. Place the slices directly on top of the hot steak so they melt.
Serve immediately.