Heat a large saucepan or dutch oven, coated with cooking oil spray, over medium heat.
Add onion and celery; cook 5 minutes, stirring occasionally.
Add carrots; continue to cook another 5 minutes.
Add broth and ginger; bring to a boil.
Add orange juice and salt. Reduce heat; cover and simmer until vegetables are very tender, about 20 minutes.
Transfer mixture (in batches if necessary) to a blender or food processor; blend until smooth.
Reheat if necessary; ladle into bowls.
Drizzle oil over soup.
Alternative method of cooking if you have a Vita Mix blender: I like to skip having to cut the carrots. I heat the onions and celery. Meanwhile, I put the other ingredients into the Vita Mix blender - carrots, broth, ginger, o.j., and salt (which I omit). When the onions and celery are cooked, I add them to the Vita Mix blender and puree the mixture on High for about a minute or so. Then, I return the mixture to the saucepan and heat it through. I ladle it into bowls and add the oil to the soup. Very easy and definitely tasty!