Julienne or cut daikon radish and carrots into thin match-like strips.
In a large bowl mix warm water, vinegar, sugar and salt until everything is dissolved. Start with 1/2 cup of vinegar and taste the mixture (If you like it more tangy/vinegary, add more vinegar).
Place carrots and daikon in a clean, sterile jar.
Fill with vinegar mixture until carrots and daikon are completely covered in liquid.
Cover jars and set in the refrigerator to pickle for at least overnight.
Pickle for 1-3 days to your desired preference (the longer time the more flavourful, pungent and sour)
Pour vinegar mixture out when ready. Pickles will last for 3 weeks in the refrigerator.