Stir 2 tablespoons of sugar into 2 cups of water in a clean 4-cup jar. Add the cup of fruit scraps. Close the jar or cover it with a piece of cloth secured tightly around the mouth of the jar. Stir a few times daily.
Depending on your kitchen environment, from between 2 to 5 days, the fruit kvass should be very bubbly and perhaps a bit frothy, while the colors of the fruit will have faded. Strain it and set aside the fruit scraps. Drink immediately or pour into bottles to increase the carbonation. After the bottles have sat in a cupboard or cardboard box for a day, burp them by slightly opening the lids. If you can't get them open for fear of spraying the drink all over your ceiling, chill them in the refrigerator to calm the drink down. If they emit no gas, let them sit another day or two to carbonate further. Burp them again to prevent explosions. Chill the bottles in the refrigerator before serving.
Make a second infusion with the fruit scraps. Concentrate the remaining fruit flavors by using less water for the second batch, about 1 cup. (Add more water if the 1 cup doesn't cover the fruit scraps.) Stir in 1 tablespoon of sugar and add the scraps. The second infusion will ferment quickly, often in less than a day. Strain the fruit kvass and either drink it immediately or bottle it as previously. Compost the pale, spent scraps.