Step 1

Preheat oven to 500°

Step 2

Pat beef dry with paper towels. Place on baking sheet.

Step 3

Meanwhile, mix softened butter and mustard together in a small bowl. Spread half of the mixture over one side of the beef with a spatula or spreader. You can use your hands but it gets messy and a lot of butter ends up on your hands and not the beef.

Step 4

Season the first half with half of the salt and pepper. Add chopped parsley if using.

Step 5

Turn the beef over. Repeat Steps 3 & 4.

Step 6

Roast in preheated oven for 25 minutes until thermometer reaches 135° for medium rare. It might take a little longer depending on your oven. If you want rare, roast to 125° and medium 140°.

Step 7

Remove from oven and rest for approximately 15 minutes. The beef will continue to cook while it rests.

Step 8

Slice 1/4 to 1/2" thick. For sandwiches, you can slice it thinner if you prefer.