Snap off tough ends of asparagus. Remove scales from stalks with vegetable peeler. Cook asparagus covered in boiling water 10 minutes, or until tender. Cut about 2 “ from top of asparagus and reserve. Set stalks aside. Coat a large saucepan with cooking spray, add butter and place ever medium. Heat until melted. Add onion, parsley & coriander to saucepan. Sauté until tender. Reduce heat to low and add flour, cook 1 minute, stirring constantly. Gradually add chicken broth. Cook for 5 minutes. Stirring constantly. Remove from heat, add reserved asparagus stalks. Pour broth mixture into a blender container and process until smooth. Pour mixture into heavy saucepan. Stir in skim milk and reserved asparagus tips add lemon juice + pepper. Cook until thoroughly heated. Garnish with lemon slices. Yield is 4 cups.