Star fruit, or carambola, comes from Indonesia. Oval shaped with five ridges, from the side it looks like a yellow star. The whole fruit is edible, skin, ridges and all. The feel and taste is like that of a grape, yet a little more sour and tart.
Green is unripe, yellow is ripe. The skin should be waxy and translucent. They do not keep long at all after harvest. Some brown along the edges is fine, even preferred, but avoid spots.
For a cute snack, cut it width-wise into little star slices. Starfruit can be diced into a relish or made into a preserve.