Put the cabbage on the cutting board stem side down and cut it in half
With a large knife, cut the stem out of each half by cutting an upside down V around the stem on the bottom to remove the tough part of the cabbage (we only want to use the leaves)
Cut each half again, in half (so that it is in quarters and easier to thinly slice)
Thinly slice the cabbage and put it in a large bowl and clean it by dunking it in cold water a few times.
Drain well and set aside
Wash the carrot, and cut thin slivers out of it
Add the carrot slivers to the bowl with the cabbage.
Peel and finely slice the onion and place a layer at the very top of the bowl on top of the carrots and cabbage.
Sprinkle the salt and oregano over the onions.
Evenly pour the hot water over the onions
Add the white vinegar and wait approximately 1 minute or until the mixture is cool before you start mixing everything together.
I find the best tool for mixing this is your hands. The cabbage will feel very stiff in the beginning and it will look like you do not have enough brine at first. While you are mixing the slaw together, you should use your hand and give the cabbage a few firm squeezes. This will release some water from the cabbage and soften it faster.
Enjoy as is as a lightly pickled slaw or as a topping on the same day, or put it in the fridge to let the flavors meld a bit more! :)