Divide the cauliflower into small florets. Put the florets (stay raw and are not pre-cooked) in a bowl with water and the vinegar and soak for about 2 hours.
Then pour off the water and leave the florets in the bowl. Wash the tomatoes, cut into larger pieces and add to the cauliflower. Mix in the yogurt and mayonnaise. Sprinkle with dill and parsley, then season with salt and pepper.