You can Gift Free ingridients to 5 random friends each day. You need at least 3 inactive friends in your street for the Van to appear. The ingredients gifted to your friends are those needed to level up a randomly choosen dish that they have at least in level 1 and with one ingredient. Each time you enter your restaurant, The 5 friends and the gift to each one, are re-randomed. But once you've helped a friend, he or she will stay in your list and marked as helped until a new day start.