If you look at the top left corner area you should see this icon and a corresponding number. The higher the heart count, the more customers you serve. More customers served, means you are making more money. The heart is affected by counters, and certain functional decor. Most of the Master trophies will add +100 hearts. Each full counter also adds hearts to your meter.
Obviously when you are working on the Mini-Quests you have to serve those dishes to your counters straight from the stove top. But you do not have to leave them there. If you need space and someday you will, you can feel free to delete them. You can also speed them up if you prefer however speedups are best left for when you have a MASSIVE amount of a super dish on your counters and you need the coins. I will cover that a bit more in depth later on. But for now, just keep your counters filled with high dishes and delete the low paying ones as you need space!
I will be adding a Super Dish list later on and you can have an idea of what dishes to watch for in order to fill your counters.