From www.leather-dictionary.com - The Leather Dictionary
A new type of food produce termed as leather was introduced towards the end of 2015. It is called "ketchup leather" and is mainly used in the fast food sector.
The preparation is quite simple: Pour ketchup onto a coated baking sheet and leave the ketchup in the oven until it is tough and solid. This is then put inside hamburgers. The ketchup leather is placed on the hamburger bun and, as it is a solid material, it does not soak the bread. The ketchup can be seasoned with all kinds of spices or garlic before the drying process.