In a blender container or food processor bowl,* combine avocados, chicken broth, onion, sour cream, milk, and paprika. Cover and blend or process until the avocado mixture is smooth and creamy.
Transfer to a glass bowl. Cover and chill for at least 2 hours. Season to taste with salt and pepper. If necessary, stir in additional milk to reach a desired consistency. Ladle into chilled bowls. Garnish with salsa, if you like. Makes 4 to 6 side-dish servings.
If you're using a food processor, process half of the ingredients at a time.