Passion fruits are native to South America. There are purple and yellow varieties, and the fruits vary in size from about the size of a plum to the size of a grapefruit. They have a shiny skin when freshly picked, and their skin becomes shriveled and wrinkled as they ripen. Their flavor is refreshingly tart when the fruit is fresh and becomes sweeter and more complex as the fruit ripens. Some people like to wait until the fruit is overripe and the pulp has an almost fermented taste. Select fruits that are well ripe, plump and heavy for their size. Fruits with wrinkle surface are actually more flavorful and rich in sugar. The easiest way to eat a Passion fruit is just scoop out the juicy pulp and discard the tough shell, which is inedible.