Bring the vegetable stock to a boil in a pot. Season with salt, lemon juice and pepper.
Peel the potatoes, chop and add to the pot.
While the potatoes are boiling, peel the asparagus lightly (the small purple leafs). Leave the buds whole, but chop the stems. When the potatoes have boiled until soft, add the asparagus and the buds for a few minutes.
Use a fork to scoop the buds out of the soup. Add the cream and the grated parmesan and blend with a hand blender until very smooth. Taste and season.
Garnish the asparagus soup with asparagus buds and croutons. Serve immediately.