Cream of Broccoli Soup

Melt butter in 3-quart saucepan over medium heat. Cook onion and carrots in butter about 5 minutes, stirring occasionally, until onion is tender. Stir in mustard seed, salt and pepper. Stir in broccoli, broth and water. Heat to boiling; reduce heat. Cover and simmer about 10 minutes or until broccoli is tender.

Place one-third of the broccoli mixture in blender. Cover and blend on high speed until smooth; pour into bowl. Continue to blend in small batches until all soup is pureed.

Return blended mixture to saucepan. Stir in lemon juice. Heat over low heat just until hot. Stir in sour cream.