Cook asparagus until tender. Cut tips from stalks and reserve. Cut stalks into 1 inch pieces and reserve. In a large saucepan sauté onion, parsley and coriander in butter until vegetables are soft but not brown. Add the flour and cook mixture stirring for 3 minutes. Remove pan from heat and stir in chicken stock to blend. Heat and simmer 5 minutes. Remove pan from heat and add asparagus stalks. Puree the mixture in a blender in batches and blend until smooth. Pour the mixture into a heavy saucepan and add the cream, parmesan cheese and asparagus tips and heat until hot. Stir in lemon juice, salt and pepper. Serve with minced parsley. If served cold, serve with thin sliced lemon.