Filet Mignon with Classic Bordelaise Sauce

Start the Steaks (Several hours before serving)

1. Fill a large pot with enough water that it fills up by about 3 inches. Place the sous vide machine in the water. Turn the machine on and adjust the temperature to 132°F for medium-rare, and 138°F for medium.
2. Divide the olive oil amongst the inside of 4 plastic baggies, preferably with a ziplock. Use your fingers to coat as much of the inside of the baggies with oil as possible. Place the unseasoned steaks in the baggies. Gently lower the baggies with the steaks into the water. The pressure of the water will create a vacuum seal around the meat. Close the ziplock just before completely submerging. Continue cooking until the desired doneness is reached. See NOTES for temperature and timing, based on the size of the filets.

Prep the Beef Marrow (Several hours before serving)

1. Place the marrow bones in a bowl filled with ice water and refrigerate for 20 minutes.
2. Remove the bones from the water and using your thumb, push the marrow out of the bones. If it won't budge, immerse the bones in warm water for about 1 minute and try again. Place the marrow into a clean bowl of ice water and refrigerate for 2 to 6 hours.

Start the Sauce

1. In a medium saucepan over low heat, melt 2 tablespoon of the butter. Add the shallots and cook until translucent, about 4 -5 minutes.
2. Add the wine, thyme, and bay leaf, and raise the heat to medium. Let simmer until reduced by about half, approx. 12 minutes. Strain the sauce into a bowl and clean out the saucepan. Discard the herbs and cooked shallots.
3. Return the strained sauce to the pan and stir in the demi-glace and ¼ teaspoon each of salt and pepper and simmer for another 4 minutes, or until sauce is slightly syrupy. Turn off the heat, cover, and set aside.

COOK THE STEAKS

1. Preheat the oven to 200°F. Heat a cast-iron skillet or another sturdy skillet over medium-high heat.
2. Season the fillets generously with salt and pepper.
3. When the pan is hot, add the fillets and cook for about 1½ minutes. Turn them over and cook another 2 minutes longer. If searing the steaks in batches, then place the first batch in the warmed oven and proceed with the remaining fillets.

FINISH THE DISH

1. Remove the marrow from the water and slice into ¼-inch thick medallions. Add the medallions to the sauce and bring it to a low simmer. Slowly simmer for 3 minutes.
2. Transfer the cooked steaks to individual plates. Use a fork to gently place 2 to 3 marrow medallions on each steak. Spoon the sauce over the medallions and steaks. Serve at once.