1. Trim asparagus, peel lower part, cut off tops and steam them about 5 minutes.

2. Heat butter in a pot, fry onion till translucent, add remaining, not steamed asparagus stalks, zucchini and potato, mix well and add vegetable stock.

3. Reduce heat and simmer 20 minutes, use hand blender to blend soup. Season with white pepper and nutmeg.

4. Serve with steamed asparagus tops drizzled with truffle olive oil.