Food trucks are everywhere in most major cities in the United States, including New York City. To understand what it's really like to run a successful food truck, we spent a full day with the crew of Yumpling, which has served traditional Taiwanese food since 2017. The day starts at 1am when co-owner Christopher Yu picks up the truck and stakes out a parking spot in Brooklyn or Manhattan. After parking the truck, Chris turns on the generator, which powers the food truck's refrigerator and freezer. Because of New York City regulations that state someone must remain in the truck while it's parked, Chris will camp out for the rest of the night. He can't sleep in the back of the truck and must remain at the wheel. The truck doesn't have heat or air conditioning, which can make for tough winters and summers. Morning prep starts at...