We have worked with a thing called "Burger of the day".
This is a randomized order that changes every day.
A "burger of the day" recipe will appear on the chefs recipe board and the customers will order it from time to time.
The '"burger of the day" is introduced in mid-levels and consists of five ingredients. These are, as mentioned, randomized which means it could be e.g five pieces of meat only or three cucumber slices + ketchup + cheese.
The results will be surprising, in a funny way of course.