Mountain Apple.

Haven't had one since I was a kid growing up in Hawaii. Unbelievable good. Hard to describe. Somewhere in between a pear and an apple.

They are native to Malaysia, but the only place I've ever seen them grow is in Hawaii. My uncle lived in a mountainous area and the trees grew there. I can't recall ever seeing them in the supermarkets in Hawaii. Maybe they're not commercially farmed.

Upon further research, I found the following here.
http://www.tradewindsfruit.com/malay_apple.htm

A very beautiful fruit, usually deep red in color, pear shaped, with a waxy skin, about the size of an apple. Flesh is crunchy, often juicy, with a mild sweet flavor. Some varieties have white or pink skin.

Description: A medium to large sized tree growing to over 60 ft in some areas. Flowering usually occurs in early summer followed by fruit ripening 3 months later.

Hardiness: Malay apple's thrive in tropical conditions and are too tender to grow outdoors in California and most of Florida.

Growing Environment: In Hawaii, Malay apples (mountain apples) commonly grow in mid-elevation rain forest areas, often as large understory trees. They do not succeed as well at sea level. Trees usually require little care other than year-round water.