½-1cupbeef stockadjust based on thickness preference of sauce
Instructions
Season the tenderloin with salt and pepper. Use less salt for a smaller tenderloin, and more for a larger one.
Heat a sous vide water bath to 130F degrees.
Place the tenderloin in a vacuum seal bag with the fresh thyme and seal.
Cook in the water bath for 2-3 hours, ensuring the bag stays submerged to allow for even cooking.
Remove from the bag, reserving the bag sauce for the red wine sauce (below).
Pat dry, ensuring the outside is as dry as possible.
Heat a cast iron skillet over medium high heat and add the ghee, bacon fat or cooking oil.
Add the tenderloin and brown for 60 seconds per side, until a brown crust forms.
Remove, slice and serve.
Red Wine Mushroom Sauce:
Heat the butter over medium heat and add the garlic and shallot. Sauté for 2-3 minutes.
Add the mushrooms and cook until mushrooms start to brown and lose their liquid, about 5 minutes. Turn the heat down if garlic starts to brown too much.
Add the soy sauce, coffee, brandy, wine and bag sauce and cook 3-5 minutes, until the alcohol has burned off.
Add the beef stock until the sauce is at your desired consistency. Add additional salt if needed.
Notes
Make sure to remove all the air from the bag so prevent it from floating. If it floats, weigh it down with a wet towel or these sous vide magnets.
Make sure your skillet is fully heated before adding the fat and the beef. It may start smoking a little when it's hot enough.
Make sure to pat the beef as dry as you can get it before searing - this allows a crust to form easier without overcooking it.
When searing, don't use a low smoke point fat like butter as it may burn over high heat. Add butter at the last 30 seconds of searing if you want that butter flavor.
The longer you cook it, the softer it will get. I do not recommend cooking more than 4 hours as the texture will begin to get mushy.
Do not cook the beef below 130F degrees for longer than 2-2 ½ hours as this can allow harmfulbacteria to form.