Peel and cut the asparagus. Bring to boil in a pot and cook until soft for approx. 20 minutes. Then drain but keep the stock.
Peel and dice the onion. Melt the butter in a pot, add the onions and then pour in the flour and lightly sautée until it has a nice yellow color. Gradually add the stock and keep on stirring.
Simmer for around 10 minutes. Then add the vegetables, sour cream, salt, pepper and the lemon juice. Blend everything until smooth.
Garnish with the croutons and serve.
Recipe Notes
*White Asparagus is the traditional choice for this dish but it can also be made with green as shown here.