Sodium Hydroxide aka lye or caustic soda is a strong alkaline compound that is used for preparing various foodstuffs. Its uses include the following.
Hominy and Nixtamal are dried maize (corn) kernels reconstituted by soaking in lye-water. These expand considerably in size and may be further processed by frying to make corn nuts or by drying and grinding to make grits.
German pretzels are poached in cold sodium hydroxide solution before baking, which contributes to their unique crust.
Black olives result from normal (green) olives being subjected to a lye-based chemical bath.
Most yellow coloured Chinese noodles are made with lye-water but are commonly mistaken for containing egg.