Best Answer for a restaurant that creates a new type of sandwich is using as a method of competition.
The correct answer should be innovation. They are being innovative and trying to create something that no one has done before and attract the customers using this technique. This is quite common in the business world and is often better than just plainly advertising old things. That's why restaurants like McDonald's or KFC always have some brand new never before seen menu items. People go and buy them to try them.