Scallion pancakes are sometimes served as a street food item but are also available in restaurants and commercially available packaged fresh or frozen solid in plastic packages (often in Asian supermarkets).
There is a story in China that pizza is an evolution of the scallion pancake, brought back to Italy by Marco Polo. A humorous newspaper article, that also includes Marco Polo inventing cheese fondue when he is lost in the Alps and wants to eat Chinese hotpot, describes the invention of pizza this way:
Marco Polo missed scallion pancakes so much that when he was back in Italy, he tried to find chefs willing to make the pancake for him. One day, he managed to meet a chef from Naples at a friend's dinner party and persuaded him to try recreating the dish. After half a day without success, Marco Polo suggested the filling be put on top rather than inside the dough. The change, by chance, created a dish praised by everyone at the party. The chefs returned to Naples and improvised by adding cheese and other ingredients and formed today's pizza.
Historical evidence in Europe suggests that pizza was not transmitted to Europe by Marco Polo, but existed in the Mediterranean long before his time. The first recorded use of the word "pizza" dates from 997 AD (in a Latin text from the town of Gaeta in southern Italy), more than 250 years before Marco Polo was born.