Combine the carrots and daikon in a medium bowl and add the sugar, salt, and vinegar. Toss to mix well.
Let stand for about 30 minutes (or more) to soften the vegetables and infuse them with flavor.
Notes
1. I like to use a mandoline to thinly slice the carrots and daikon. Alternatively, you could use a food processor fitted with a slicing blade, shred them in a food processor fitted with a shredding blade, shred them using the large holes of a box grater, or cut them into matchstick pieces with a sharp knife.2. These pickles are ready to eat after 30 minutes, but they are even better after they’ve sat for several hours or overnight.3. You can store the pickled vegetables in a covered container in the refrigerator for up to 2 weeks.