There are five steps to making a cream soup:
- Cook the starch*. Most cream soups have a flour base and often an onion for flavoring. Sauté the onion in butter. Add the flour and cook while stirring until the butter and flour is combined into a thick paste. The cooking should only last a minute or two and the flour should not be browned.
- Cook the soup base. While still cooking, pour a little of the stock into the flour and stir to dissolve. Add the rest of the stock and simmer for ten minutes. Your soup base should thicken as it cooks to the consistency of a light sauce.
- Add the vegetables. Add and cook the vegetables until they are tender. Salt and pepper to taste. (The amount of salt will vary depending on the sodium in the broth.)
- Puree the soup. Pour the soup into a blender in batches and puree until smooth. Pass the pureed soup through a strainer to catch any lumps. Press the lumps through the strainer with the back of a spoon. Discard any solids.
- Finish the soup. Add the cream, thin with more water if necessary, and adjust the seasoning.
*Wheat flour is typically used as the starch in cream soups. For those who are gluten intolerant, you may use corn starch or a starchy potato. When the potato is pureed, it will thicken the soup.