Native to South America, this egg-shaped fruit is also known as a tree tomato. Although not yet widely accepted in the United States, the tamarillo is very popular in South and Central America, the Caribbean, and parts of Asia, New Zealand (from where most of the fruit in the United States is imported) and Australia. The tamarillo has a tough, bitter skin that can be various glossy shades of red, purple, amber or yellow. The tart but very flavorful golden pink flesh is purple-tinged around the seeds. Tamarillos are available from May through October in specialty produce stores and some supermarkets. Choose firm, blemish-free fruit that's heavy for its size. When ripe, tamarillos should be fragrant and should yield slightly to palm pressure. They can be ripened at room temperature. Once ripe, they should be refrigerated, tightly wrapped in a plastic bag, up to 10 days. Tamarillos can be eaten fresh or cooked, and are used for both sweet and savory dishes. One requisite, however, is sugar, which reduces the fruit's natural tartness and enhances its flavor. Tamarillos are a good source of vitamins A and C.