Creamy Carrot Soup

3T butter or oil
1 small onion, sliced
1 pound carrots, roughly chopped
1 large starchy potato, peeled and roughly chopped
salt and pepper
5 cups stock
1/2 cup cream (optional)

1. Put the butter or oil in a large, deep saucepan over medium heat.
Add the vegetables. Stir with salt and pepper and cook for about 15
minutes. Add the stock and cook until the vegetables are very tender,
15-20 minutes.
2. use an immersion blender to puree the soup.
3. if you want to include cream, add just before serving.