Use a vegetable slicer and thinly slice your cucumbers and onions, then add them to a medium size mixing bowl.
Peel your carrots and thinly slice them, then add to the bowl of cucumbers and onion as well.
Add in 4 cups of seasoned rice vinegar and 3 tablespoons of sugar, then mix together.
After mixing either cover the bowl with foil or poor it into a food storage container and place the cucumber salad in the fridge.
It's ready to eat immediately but the longer it can marinate the better. I like it best the following day!