- In a saucepan, sauté the onion in the butter. Add the asparagus and cook for 1 minute.
- Add the broth and rice. Cover and simmer until the asparagus are tender, about 15 minutes.
- In a blender, purée the soup until smooth, then pass the soup through a fine sieve to remove the remaining fibers. Season with salt and pepper.
To keep asparagus longer, wrap them in a wet towel, stored in a plastic bag in the refrigerator. Freezes well.