Starfruit or Carambola

Starfruit, also known as carambola, has five ridges running lengthwise, 

and when cut into cross-sections, the cut sections are the shape of a five-pointed star, or a starfish. 

They are grown in tropical areas such as Florida, Hawaii and Puerto Rico and originated and are particularly popular in Southeast Asia. 

I recall eating it a few times in Hawaii. 

I bought one at an Asian market recently and have also seen them at our local Albertson's. Wikipedia says they are ripe when yellow with a light shade of green and have brown ridges at the five edges. 

They are overripe when they start to get brown spots. The one I purchased had quite significant green toward the ridges and I think I let it sit too long before eating it as it had the brown spots, but it was still fine. 

The skin is sort of waxy and the flesh is very crunchy and juicy, but does not have a lot of taste. Part of its popularity in the tropical areas is the fact that it is so juicy which helps to counter the sweltering heat. In that way, it is compared to watermelon, although I believe the watermelon has significantly more flavor in its juice. Starfruit is one of the 1001 Foods You Must Eat Before You Die. 1001 says it has "notes of pear, melon, and gooseberry" while Wikipedia says it "has been likened to a mix of apple, pear and citrus family fruits all at once." It is supposed to be a good palate cleanser. I added some sugar, sucralose and lime juice to various pieces and liked the additional flavor that was added to the juice, particularly by the sucralose. Best, however, was some starfruit we were served in the Amazon Basin rainforest outside of Puerto Maldonado, Peru. 

We were served a fruit plate that included starfruit and honey. Honey on the starfruit was very good.