Cream of Fresh Asparagus Soup II

INGREDIENTS

• 1 pound fresh asparagus, trimmed and cut into 1 inch pieces
• 1/2 cup chopped onion
• 1 (14.5 ounce) can chicken broth
• 2 tablespoons butter
• 2 tablespoons all-purpose flour
• 1 teaspoon salt
• 1 pinch ground black pepper
• 1 cup milk
• 1/2 cup sour cream
• 1 teaspoon fresh lemon juice