Cut the pork belly into strips across the short side, in the width you prefer.
Place the strips in the vacuum bag, arranging them in one flat layer without overlapping.
Vacuum seal the bag.
Set your sous vide to 85 degrees Celsius (185 degrees Fahrenheit) and let the pork rinds cook in the water bath for 100 minutes.
Take the pork rinds out of the bag and pat them dry thoroughly with a dry cloth or tea towel. Avoid using paper towels as they will stick to the rinds. It is important that they get very dry. Rub salt into them.
Now place the rinds on a baking rack. Make sure there is some space between them.
Put the rack in a preheated oven at 200 degrees Celsius (392 degrees Fahrenheit) convection and let them roast for 20 - 25 minutes until they become deliciously crispy and golden!
Take the crispy rinds out of the oven and let them cool on the rack.
Enjoy your meal!
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Notes
I have tested making an entire pork belly (that had been only scored) using the same recipe. It did not become particularly crispy, so they should always be cut into strips beforehand.