Wash the asparagus, cut off the woody ends. Peel the asparagus. Put asparagus peels in 1 1/4 litre of boiling salted water with a pinch of sugar. Cover and simmer for 20 minutes. In the meantime, cut the asparagus into small pieces.
Peel and wash the carrot and potatoes and cut them into small cubes. Clean, wash and finely dice the zucchini. Pour asparagus skin on a sieve. Collect the asparagus water, pour it back into the pot, bring to the boil and add the asparagus pieces.
Cover and cook for about 15 minutes. Heat the oil in a pot. Fry carrots, potatoes and zucchini briefly. Add 3-4 tablespoons of water and cook covered for 5-6 minutes. Drain the asparagus, collect the asparagus water.
Melt the fat in a pot. Sweat flour in it. Add asparagus water while stirring constantly. Add crème fraiche. Season to taste with salt and pepper. Add asparagus pieces to the soup. Serve the asparagus soup with the diced vegetables.
Garnish as desired with chervil.