Place an enameled cast iron dutch over over medium/high heat. Add oil and diced onion. Cook to desired doneness. See Note #4 below.
Add garlic to Dutch Oven and saute for approximately 1 minute.
To the pan add cut mushrooms, salt, pepper and thyme. Cook until the mushrooms have released their moisture and reduced slightly, about 8-10 minutes. See Note #5 below.
To the mushrooms add the flour. Stir and cook for 1-2 minutes. Add wine and simmer for another 1-2 minutes.
Pour in broth and bring to a simmer over the same medium/high heat until thickened and then lower heat to medium.
Stir in milk and bring to a simmer. Take of heat and serve immediately. This soup can be eaten as is or be garnished with fresh chopped parsley or chives, red pepper flakes or parmesan cheese.
Recipe NotesNote #1- The stems on Shiitake mushrooms are too fibrous for pleasant eating and should be removed before cooking. To remove hold the base of the mushroom in one hand using your fingers and using the other hand pinch and pull the stem from the base.Once removed, the stems can make a wonderful broth for either this soup or to be used at a later date. Note #2- For the white wine either dry Sherry, Sauvignon Blanc, dry Marsala or Pinot Grigio all work well.Note #3- For extra creamy Mushroom Soup use 4 cups beef broth and 1 1/2 cups heavy whipping, following the directions as written.For a moderate amount of creaminess use 2 cups milk and 1 cup half and half.For a vegan or non-dairy option use 3 cups unsweetened flax milk, unsweetened almond milk or soy milk. Note #4- For caramelized onions place an enameled cast iron dutch oven over medium heat. Add the oil and the diced onion to the pan and give the onions a quick stir. Let the onions cook stirring every 10 minutes or so until they reach a deep caramel color. This will take about 45 minutes to 1 hour to complete. (For a 15 minute caramelized onion technique click here.)For translucent onions cook over medium high heat stirring often until the onions loose their opacity, about 10-12 minutes. Note #5- Dehydrated Shiitake, wild mushrooms or portobellos may be used for this soup. Add them in step 3 but only cook for a few minutes before adding the flour and then the broth. Note #6- Cooking times will vary depending on whether onions are cooked to caramelization.