Overdue recipe 2: Cream of Mushroom Soup (creamless & flourless)

I am a big fan of creamy mushroom soup, and I count the Mushroom Stroganoff at Soup Spoon as one of my favourites for its chunky mushroom pieces.  However, I decided to make my own version on one of my thesis-churning days after I recently happened to know that the soup contained flour.  Frequently, flour, which I suppose in this case is all-purpose (AP) flour, is used surreptitiously to thicken soups.  And I don't like the idea that I am eating empty carbs in the form of nutrition-less white flour.  I am not trying to count calories here...Soup Spoon states that its mushroom soup has a caloric value of 275, and how much of it is derived from flour?  In addition, because AP flour is derived from wheat, gluten-intolerant or sensitive people would not be able to digest the soup very well.

What is the alternative to making a creamy mushroom soup without using flour?

Cream of Mushroom Soup (creamless & flourless)

(Adapted from Mushroom Bisque, The Earthbound Cook by Myra Goodman, p. 22)

Note: In this recipe, I am just going to give general instructions without exact amount of ingredients used.  This is because I cooked the soup a long time back during thesis-churning days, haha.

Ingredients

• Cooking fat (I used butter)
• Garlic cloves (minced)
• Red onion (diced)
• 4-5 varieties of diced mushrooms, including crimini, shiitake, enoki types (I must tell you, I went the easy way of buying this huge value packet of mushrooms for steamboat purposes from NTUC supermarket, haha!)
• Vegetable broth*
• Arrowroot starch
• Italian seasoning (optional)
• Dried thyme (to garnish)
• Ground black pepper (to taste)
• Sea salt/nama shoyu (to taste)

Directions

1. Melt butter in a large saucepan over medium heat.
2. Add garlic and onion to stir-fry for about 3-5 minutes.
3. Add mushrooms (and Italian seasoning) and saute them until they start to soften and ooze out water, which takes about 5-7 minutes.
4. Add vegetable broth and let the mushrooms simmer away for about 10 minutes.  At this point, you may choose to reduce heat to avoid uncontrolled drying of the liquid.
5. Remove heat and let mushrooms sit to cool for about 5 minutes.
6. Transfer them to a high-speed blender.
7. Add arrowroot starch.  (You don't really have to add much of the starch, say about 2-3 tbsp at most, to thicken the soup because when you blend the mushrooms, the soup is naturally thickened.)
8. Blend the mushrooms and arrowroot starch mixture till it takes on a coarse pureed consistency.  Unless you want a baby-feed like consistency, please go ahead and blend away.
9. Transfer the soup to a bowl, add ground black pepper and salt to taste, and garnish with dried thyme before ready to serve.

Additional notes

• I am still a novice when it comes to playing with temperate herbs like thyme, rosemary, basil and stuff like that.  I used Italian seasoning for the sake of experiment and I think the variety of herbs in the seasoning added some complexity to the mushroom taste.  In the original recipe, the author used dried thyme to saute with the mushrooms.
• I think packaged vegetable broth is not common in mainstream supermarkets.  I bought mine from Cold Storage for about 7 SGD at about 950 ml.  Quite expensive.  You can choose to use vegetable stocks, but I discourage it because I don't like the food additives, especially MSG, inside such stocks.  For economical purposes, you can make your own vegetable broth or bone broth and store it in the refrigerator for future use.  
• Vegetable broth - Dump any kind of vegetables you like into a large pot and boil them for about 3-5 hours to extract the vegetable essence.  Some ideas are carrots, sweet potatoes, leeks, onions, celeries, cabbage etc.
• Bone broth - If you are a big fan of traditional Chinese meat broths, this should not be too surprising for you.  Just grab generous amounts of soup bones and boil them to extract the marrow.