Green soup

Favoured by that 's is cold in this season and the need to have a break from this fanciful cooking, I decided to make a green depurative soup.
As usual I start making a low-fat soup but I finish with a very rich one.

Ingredients for two people:
2 tablespoons of chopped white onion
500 g broccoli
1 zucchini
3 medium potatoes
1 celery rib
some leaves of parsley
a little piece of  fresh ginger (2 cm more or less)
water
extra virgin olive oil
salt
4 tablespoons lemon juice
100 g grated Parmesan

Preparation:
I pour in a pan the extra virgin olive oil and chopped ginger and onion.
 I sweat all for two-three minutes then I add chopped broccoli, zucchini,parsley and celery.
i cover with water, I add salt and I let it cook for 20 minutes over a low flame.
I blend all and I add lemon juice , let it flavour on a stove for two or three minutes.
As it seems too low-fat...I make some leaves with grated Parmesan.
I serve  the soup very hot.

We like this soup, we go for seconds...but just to have a bigger depurative effect!