Pumpkin Curry Soup

I have been trying to watch my carbs lately for weight loss and some overall health issues, so vegetables are on the main stage.  This soup is very filling and tastes like Fall in a bowl.

1 TBSP olive oil
1 large red onion (softball size)
6 stalks celery (about 8" long)
1 1/2 cups chopped bok choy or other cabbage
1 6oz package sliced white mushrooms
4 cups chicken broth
1 15oz can solid pack pumpkin
1 tsp dried coriander
1 tsp dried curry powder
1/2 tsp dried ground sage
2 TBSP butter
1/4 cup heavy cream
salt and pepper to taste

In a stockpot or dutch oven, heat oil and saute onions and celery. Once they have softened, add cabbage and mushrooms and cook until they are wilted. 
Add chicken broth and bring to a boil, adding water to cover vegetables if needed. Reduce heat to medium and simmer 45 minutes to 1 hour until everything is mushy soft. Puree with an immersion blender until smooth and add pumpkin and spices. Cook another 10 minutes and add butter and cream and salt and pepper soup to taste. Serve topped with a dollop of sour cream or plain yogurt and a few toasted pumpkin seeds to garnish.

**If you are more concerned with calories and fat than carbohydrates, you may want to reduce the butter to 1 tablespoon and use 1/2 cup milk or half and half instead of the heavy cream.