Heat oil in a medium saucepan over medium high heat. When hot, onion and garlic and cook until onions start to soften, 1-2 minutes. Add mushrooms amd thyme, cooking an additional 3 minutes.
Add broth, cover with lid, reduce heat and cook for 10 minutes.
After cooking, taste and add salt and pepper as needed. Remove about ¼ cup of liquid and put in a small bowl. Add cornstarch and soy milk, then whisk until smooth. Add to the pot. Heat, stirring frequently until soup thickens.
Tips for BEST Results:Choose fresh mushrooms that are free of spots, don’t feel slimy or sticky and have a fresh earthy smell.Be sure to mix the cornstarch with the liquid before adding it to the soup. This prevents the cornstarch from clumping when it’s added to the soup.To save and reheat you can store it in the refrigerator or freezer. To reheat, place in a pot. When heated if it seems too thin, simply mix up some cornstarch with a bit of liquid from the pot and then add to the soup. Keep heating and stir until soup thickens.