For a delicious breakfast, squeeze a wedge of lime over a halved papaya. Most grocery stores, especially the Chinatown minimarts, carry a large stock of this sweet fruit during this time of year. Replete with vitamins A and C, papayas mostly come from Hawaii, but California, Florida, Mexico, Puerto Rico and some Central and South American countries produce smaller quantities of the fruit as well. Although papayas can be purchased year-round, they peak in early summer. As the fruit ripens, it changes color gradually from green to yellow-orange, beginning first at the bottom and progressing toward the stem. At the store, choose papayas that are half yellow and store at room temperature for a few days to let them fully ripen. When gently squeezed, the fruit should yield slightly.