A cook, also known as a supplier, is a person or a business entity that sells something. A vendor generally finds somewhere to purchase their goods and services. After acquiring the necessary items, the vendor markets and sells their wares through whichever method works best for them.
For example, if it is a food truck, the vendor ensures there are enough supplies to make items on the menu and feed an expected number of customers, then drives to a target area and begins selling food.