Slow Roasted Beef Tenderloin (Chateaubriand)

Beef Tenderloin
1 Cover your tenderloin with kosher salt. Let it sit in the fridge for 4 hours. Remove it from fridge 1-2 hours before roasting.
2 Pat dry your tenderloin well and add some pepper. Place on a roasting pan or a baking sheet with a wire rack. You don't want the bottom of the tenderloin touching the pan.
3 Roast at 250°F for 1-2 hours or until roast reaches internal temp of 118-120°F for a medium rare. See notes for other temperature options.
4 Let it rest at least 20 minutes or right until serving. 
5 Sear on all sides until golden in a pan or grill.
Béarnaise Sauce
7 Melt your butter and let cool. I sometimes brown my butter for a richer, nutty flavor.
8 In a pan, add your shallots, vinegar, wine, dried and fresh tarragon. Turn heat on to medium low and let it cook until all the liquid absorbs. Set aside to cook.
9 Fill a small saucepan ⅓ of the way up with water and bring to a simmer.
10 Add the yolks to a bowl with the shallot and tarragon mixture, white pepper, tabasco and about 2-3 tbsp of the butter.
11 Whisk the yolks over the saucepan. Whisk vigorously until they turn a very pale yellow, adding in your water at this point. It should be about 45 seconds to 1 minute MAX.
12 Remove from heat and emulsify the rest of the butter in VERY slowly. It should look like a thread of butter going in. When you are almost done, reheat a little bit of butter and slowly add to reheat the sauce.
13 Once its all done, add chives and salt to taste and that is it!