Boil 4 quarters of water. Meanwhile, peel and cut potatoes, carrot, divide cauliflower into florets, wash and cut parsley.
When water is boiled, blanch the tomato for 30 sec. Take out tomato and add potatoes to boiling water, set timer for 10 min.
Peel and cut tomato and add to soup. Add parsley and carrots as well.
After 10 min, add cauliflower, salt and pepper and a little olive oil, if desired. If using zucchini, now is a time to add it as well. Set timer for 10-15 min, depending on the size of your florets.
You are done! Cauliflower prices should be firm. This soup goes well with sour cream.