1. Clip the immersion circulator to the side of a large container (I prefer this sous vide container) and heat to 129F.
2. Pat the flank steak dry and season with half the salt and pepper on both sides.
3. Place in a plastic bag and seal with a vacuum sealer (I like to use a Foodsaver for the best results). To make it airtight, use a ziplock bag and slowly drop it into the water while sealing it.
4. Place the bag in the water once the water has reached the proper temperature. If it floats, clip the bag to the side to keep the meat fully submerged in the water.
5. 2 hours in the oven
6. Remove the bag from the water and place it in an ice bath for 10 minutes.
7. Take the beef out of the bag and pat it dry with paper towels. Season with the remaining salt and pepper to taste.
8. Warm a skillet over high heat with a high smoke point oil (ghee is my favorite, but you can use vegetable oil, avocado oil or coconut oil).
9. Sear the meat for 2 minutes per side, or until a brown crust forms on each side.
10. Remove from the skillet and set aside for 10 minutes to cool. Serve it with the peppercorn sauce, sliced against the grain (below).

Peppercorn Sauce:

1. Reheat the skillet you used to cook the steak on medium heat while the steak rests. Cook for 1 minute after adding the brandy to deglaze (until the alcohol has burned off).
2. Bring the peppercorns, salt, and beef broth to a simmer.
3. Stir in the cream and cook for 3-4 minutes, or until the sauce coats the back of a spoon. If desired, season with additional salt.