Cut 2-3 asparagus spears into small pieces. Heat the fat. Briefly sauté the flour in it. Stir in asparagus stock, bring to the boil. Simmer the asparagus pieces for about 10 minutes. Stir from time to time. Season to taste with salt, pepper, sugar and lemon juice
Remove soup from the stove and possibly alloy it. For this, whisk the egg yolks, 75 g cream and 2-3 tbsp. soup and stir into the hot soup (do not boil any more!). Whip remaining cream until half stiff, stir into the soup in streaks. Finally garnish with chervil and crushed berries