Rinse the mushrooms with cold water to remove any dirt or debris, and pat dry with paper towels (do not soak them). Slice half of the mushrooms and roughly chop the other half. Set aside.

Heat 1 tablespoon of olive oil over medium-high heat in a large soup pot or Dutch oven. Add the onions, cook for about 4 minutes, then add the garlic and cook for another minute. Stir in the mushrooms and a good pinch of salt and pepper. Cook, stirring regularly, until the mushrooms start to brown, about 8-10 minutes. Spoon out 3 tablespoons of mushrooms and keep them for later (if you like to serve the soup topped with mushrooms).

Stir in the second tablespoon of oil and the flour and cook, stirring, for about one minute. The flour, the oil, and part of the mushroom moisture will form a roux paste that will thicken the soup.

Add the vegetable broth and stir while returning the mixture to a boil. You want to dissolve all of the flour from the bottom of the pot. After a couple of minutes, as soon as the liquid comes up to a simmer, reduce the heat to medium-low and add the milk and the thyme.

Simmer uncovered, stirring occasionally, for about 15-20 minutes.

Finally, add the soy sauce and cook for a further minute. Taste and adjust seasoning, as necessary (I use light soy sauce and ¼ teaspoon of salt - that depends on the salt content of your soy sauce and broth).

Spoon the soup into bowls, garnish with the remaining mushrooms and a drizzle of olive oil, and serve immediately with crusty bread on the side. Enjoy!