In a medium saucepan, heat the vinegars, sugar, and salt. Keep stirring until the sugar has fully dissolved.
In a large bowl, toss vegetables together. Pack into jars, pour vinegar mixture overtop to cover, and refrigerate. Atzara keeps for several weeks in the refrigerator.
Notes
Green papayas (a.k.a. cooking papayas) are available at most Asian grocers. You can use a papaya that is starting to turn orange and is still hard, but avoid a soft, ripe papaya.