Tripe is the stomach of a cow, pig or sheep. It's available in two variants. Green tripe is raw offal and has the animal's undigested stomach contents on its surface. Green tripe is used as pet food. Gray tripe is cleaned, bleached and deodorised by a butcher before it is sold as white tripe. It's cleaned with a food-grade, oxygen-based solution that should be used only by a professional, However, you can clean green or grey tripe at home to make it whiter.
Rinse the tripe in cold water. Lay it on your work surface.
Rub rock salt on the tripe. Flat tripe is easier to clean than honeycomb tripe, whose greater surface area and smaller pockets of tissue hold residue.
Rinse the tripe in cold water to remove excess salt. Repeat if necessary.
Place the tripe in a large saucepan. Fill the pan with cold water. Add 7 tbsp of salt per gallon of water and bring water to a boil. Cover pan.
Boil the tripe for up to three hours. The tripe will look whiter. It is now ready to use in your recipe.
Tripe becomes softer the longer it is cooked. Boiling before cooking improves its texture. Cooking tripe in a slow cooker or crock pot makes it tender.
Never attempt to bleach tripe by using household bleach.