Most people let starfruit ripen until some of the edges start to turn brown and the fruit is yellowish in color.
Slice starfruit thinly or thickly for various garnish applications. Try floating super-thin slices on the top of cocktails (particularly those involving tequila), or hooking thicker slices onto the edge of glasses.
Thin starfruit slices can also be dried in the oven for a different look and texture as well as a more intense flavor. Slice the fruit as thinly as possible using a serrated knife or mandoline, then dip each slice in simple syrup. Shake off any excess and dry on silicon baking sheets in an oven with the temperature set as low as possible (expect this process to take hours). When the slices are firm (but not crisp), move them to cooling racks.
Beyond the visual applications, star fruit can be paired with yogurt, cilantro, avocado, bananas, cream, basil, mint, shrimp and other seafood. In addition to being served raw (peeled or unpeeled), it can be sautéed or grilled and used in soups and sauces.