Rambutan, also called hairy lychee, is a fruit of hazlenut size with reddish brown skin. This fruit is quite similar to lychee and has a few similarities with longans. The taste is mildly sour, juicy, and sweet with citrusy hints. The seeds are grape-like and also edible. Rambutan is one kind of fruit one won't forget once seen. It is spikey, flaming red on the outside, and its taste almost matches its appearance! Rambutan season runs during summer, from May through September.