Combine the water, vinegar, sugar and salt in a saucepan over medium heat. Stir until the sugar and salt dissolve and the brine is clear. Pour into a bowl and let cool to room temperature.
Add the shredded carrots to the cooled brine. Let sit at room temp for 20-30 minutes before serving or transfer to a lidded jar and store in the fridge up to 5 days.
Notes
Can do half carrots and half daikon. Can use rice vinegar instead of white vinegar for a more subtle sour flavor.Add fresh chilis if you like it spicy!