Take your filets out of the fridge 20- 30 minutes before you are planning to cook them so they can come to room temperature.

Sprinkle the Kosher salt and fresh ground pepper on both sides of each filet. A good seasoning of salt and pepper is a great way to ensure a good steak.

In a heavy skillet or cast-iron pan, heat the olive oil over medium-high heat.

When the pan is very hot, add the filets and sear for 2-3 minutes on the first side.

Turn the beef over and sear on the other side, then turn the heat down to medium and add the sliced shallots.

Continue cooking until the temperature on an instant-read meat thermometer reads 125 degrees F. for medium-rare or to the desired temperature.

Remove the beef from the pan and allow it to rest while the sauce is prepared.

Add the balsamic vinegar to the skillet to deglaze the pan using a wooden spoon to scrape up any brown bits from the pan.

Add the beef stock, Dijon mustard, and grainy mustard, and stir to combine.

Bring the liquid to a boil and simmer rapidly for 2-3 minutes, stirring occasionally, allowing the sauce to reduce slightly.

Reduce the heat to low and add the butter to the pan and stir until melted.

Make a slurry mixing the cornstarch and water together.

Add about ½ the slurry to the pan and simmer for 1 minute. If you would like your sauce a little thick, you can add more of the cornstarch slurry. (Note: the sauce should be a little thicker than an Au Jus but not as thick as a traditional gravy.)

Serve each of the filets with about 2 Tbsp of sauce over each. Enjoy!