Preheat the sous vide cooker: Fill the sous vide container or a large pot halfway with water and set the Sous Vide Precision Cooker to 132°F (55.6°C).

To make the seasoning, whisk together garlic powder, paprika, salt, and pepper in a small mixing bowl.

Season the cod by rubbing it with olive oil on all sides. Then, rub the seasoning mixture all over each cod fillet.

Place the fish in a zip-lock bag with the sliced lemon and seasoned cod. Arrange them in such a way that they remain in a single layer. (A single layer ensures even cooking; if your bag is too small, use multiple bags.)

Vacuum seal the cod: Using the “water displacement” technique, vacuum seal all but one corner of the bag. Slowly lower it into the water bath, making sure that everything below the zip-line is submerged. Then, seal the remainder of the bag.

Sous vide the fish: Cook the cod for 30 minutes in a warm water bath. (Make sure the cod is completely submerged in the water; if it isn’t, use sous vide weight magnets or kitchen metal tongs to secure it in place.)

To serve sous vide cod, remove the bag from the water bath and carefully remove the cod from the bag. (Because cooked cod tends to fall apart easily, I recommend carefully removing it from the bag and transferring it to a plate with a fish spatula or your hand.) Sprinkle with optional chopped parsley and serve immediately.