Step 1

Fill a large pot with water. Attach an immersion circulator to the pot. Set the temperature to 130 degrees F (54 degrees C) and the timer to 35 minutes.

Step 2

Season cod lightly with salt and pepper. Zest 1/2 of the lemon over each piece. Slice lemon. Place butter and 2 lemon slices over the lemon zest. Place 1/2 of the shallot slices in the bottom of a resealable bag and place 1 cod loin on top. Repeat with second piece of cod and remaining shallot slices. Close the bags, leaving 1 small corner open.

Step 3

Lower the bags into the water and submerge until all the air has been expelled. Close the corners.

Step 4

Wait until timer goes off and remove the bags. Carefully transfer cod onto 2 plates. Drizzle 1 tablespoon of cooking liquid from the bag over each cod loin. Garnish with extra lemon slices.