Known as do chua, these Vietnamese pickles lend crisp, crunchy texture to banh mi sandwiches, but can also be eaten with rice or noodles.
In a medium bowl, combine the carrot and daikon. Add the salt and 2 teaspoons of the sugar and massage into the vegetables until the daikon is flexible enough to bend in half without snapping (the opposite ends should touch), 2-3 minutes. Rinse the carrot and daikon under cold, running water, then drain and pat dry. Place the daikon and carrot in 1 clean glass quart jar or 2 clean glass pint jars.
In a medium bowl, combine the vinegar, water, and the remaining ½ cup sugar and whisk to dissolve the sugar. Pour the brine over the daikon and carrots, leaving about ½ inch of space at the top. Screw on the lid, turn the jar upside down a few times to distribute the brine and refrigerate at least overnight and up to 1 week. If possible, occasionally flip the jar over to mix the brine and vegetables around a bit.