There are lots of restaurants in Cook It!, but only Sushi has so many dishes that it requires its own menu! You can visit this menu by clicking the button on the top of your screen while within a Sushi Level. It won't show many dishes at first, but as you advance through the restaurant, more will unlock. Just in case you can't find it, though (or if you want to see everything sushi has to offer), you can check out the image below to see what the complete menu looks like: