If you haven't bought fillets, you need to fillet your fish. There are 2 fillets on the top side and underside.

Start by trimming the edges so you have just the clean fillets left.

Take a long, thin, and flexible/soft knife and make a cut along the bone in the middle. Slice downward at an angle into the skeleton while cutting away from the central bone. This way, you get all the fish with the fillet free. Repeat for the other three fillets.

Place the fish on a cutting board and sprinkle salt on both sides. This is a gourmet salting that helps extract moisture from the fish and makes the flesh firmer.

Set your water bath to 52 degrees Celsius (126 degrees Fahrenheit).

After 10 minutes of brining the fish, rinse them off under cold water - under the tap. This removes the salt and stops the brining process.

Pat the fish dry thoroughly (I always use a clean tea towel) and carefully place your fillets in a vacuum bag.

Place the bag in the water bath and cook the fish for 20 minutes.

Carefully take the fish out - it is very delicate, so use a spatula or similar to remove it. Pat it dry with a clean tea towel or kitchen paper and serve immediately.