kind of green cream of celery soup

I'm drinking this soup as I write this and enjoying it immensely. It has the taste of spring, but is warming on this quite nasty and ridiculously cold day. And it's very pretty, a pale green that hints of spring. I followed the recipe almost exactly--I had no scallion so used a bit more onion. I had stock I had made from ends of asparagus and used that instead of regular vegetable or chicken stock. And I finished with some plain yogurt instead of sour cream. I don't think these changes are substantive and I must say the result is luscious. I will be making this again.