Take a look at your social network feeds. People LOVE to take pictures of their food, no matter how gross it looks. Look at this [fish & chips] [hamburger] [pasta bowl] I ordered! So why not create a community around that? Users can share pictures of what they ate and where they ate it.
The user orders food, and when it comes out, they tag the restaurant, take a picture, and title the dish. Two hours later, the app gives them one reminder to rate it if they want to with ew, fine, or yum! Maybe there could be some magic filters that make the food look less gross in pictures.
I enjoy cooking, but sometimes the recipes I use need a little tweak here and there. I propose an application that allows for reflection. Users can add an entry with the name of the recipe and the source of the original. They can take in-process pictures, or just a final. At the end of the process, the user is asked to share thoughts on what they might do differently - reduce the salt, add more oregano, increase cooking time on their oven, etc. There could be some sort of social aspect to this, but it would be predominantly for self-journaling.