Step 1

Season steaks with 1 teaspoon of the salt and ½ teaspoon of the pepper, and place 1 sprig of thyme on top of each steak. Place 2 steaks, side by side, into a sous-vide bag (18 x 16.5 cm - see Tips). Seal using a vacuum sealer as per manufacturer’s instructions (see Tips). Repeat with another sous-vide bag and remaining steaks.

Step 2

Insert blade cover and press down to secure. Place sealed bags with steaks into mixing bowl and add enough water to fully submerge bags (not higher than the 2L maximum fill level). Remove bags from mixing bowl and set aside. Add lemon juice to mixing bowl (see Tips) and warm up Sous-vide /15 min/55°C.

Step 3

Place sealed bags, side by side, into mixing bowl, ensuring bags are completely covered with water, then start Sous-vide /1 h 30 min/55°C. Carefully remove bags using tongs. Remove steaks from the bags, discard thyme, thoroughly pat steaks dry with paper towel and set aside. Empty mixing bowl and remove blade cover.

Step 4

Place eschalots and tarragon into mixing bowl and chop 5 sec/speed 5. Scrape down sides of mixing bowl with spatula.

Step 5

Add wine and vinegar, then cook 5 min/100°C/speed 2. Meanwhile, place a non-stick frying pan over medium-high heat, add 1 tablespoon of the butter, then add steaks and sear for 40 seconds per side. Remove from pan and allow to rest for 5 minutes before serving.

Step 6

Add remaining 200 g butter, egg yolks, remaining salt and pepper to mixing bowl and emulsify 4 min/70°C/speed 4. Serve steaks with Béarnaise sauce.