Apple bananas are small, sweet dwarf bananas commonly found throughout South America, Mexico and Malaysia and there are several growers in Hawaii. The flavor is the similar to the common banana and can be used interchangeably. These bananas have become more popular throughout the U.S. and can be found in most Asian grocery stores and many well-stocked grocery stores such as Whole Foods. We have seen them at some Costco stores as well.
We love these bananas because they are the perfect size and are roughly half the size of the more common large bananas sold in the U.S. The flavor is slightly tart but nicely sweet.
When you buy apple bananas they may be quite green but you can just let them sit on the counter for a day or two and they'll ripen right up.
Apple bananas are use in desserts when they are very ripe. You can fry them and serve them with ice cream, Thai style. I haven't tried it yet but I'm sure they'd make a perfectly wicked banana cream pie.
Hawaii is a significant producer of apple bananas. In 2001 there were about 1700 harvested acres but as of 2012 that is down to less than 800 harvested acres.