Dice chicken skin into small pieces of about ½-inch in diameter. This is best done with a knife while the skin is frozen, or scissors if it’s been defrosted.
Bring a large pan to medium heat. Add chicken skins and salt to pan, and cook for about 15 minutes.
Add onion slivers to the pan, and stir well with the chicken. Lower the heat to low to prevent the chicken from burning, and continue cooking for about 20 minutes.
Strain the gribenes through a fine mesh sieve, collecting the resulting chicken fat (schmaltz) in a jar.
Return chicken and onions to the pan, and cook on low heat for another 20-25 minutes, until they become crunchy and browned (take care not to burn).
Gribenes will keep in an airtight container in the fridge for 4 days. It can be used anywhere you would use bacon - atop salads, in GLT (Gribenes, Lettuce and Tomato) sandwich, or folded into an omelet.
Schmaltz will keep for a week, or 6 months in the freezer. It can be used to fry potatoes, or in place of butter in savory pastries.