This tree, native to Southeast Asia, has been widely planted in tropical and subtropical parts of the world. There are two commonly sold varieties, tart and sweet, which are difficult to tell apart by sight but the sweet ones tend to have thicker ribs. The main use of Carambola in the U.S. is as a decorative addition to fruit salads and similar dishes. Carambola is more cold tolerant than Bilimbi so is grown commercially in South Florida and in Hawaii. The photo specimen was typical of what we get here in Southern California, 6-3/4 inches long, 4 inches across and weighed 14-3/4 ounces. It was very juicy and tart-sweet, a bit more tart than a tart apple but not at all unpleasant.
More on Oxalis.