Make vegetable stock according to directions, or if in a hurry use store-bought stock.
Cut the onion into quarters and thinly slice. In a frying pan, heat some oil until hot and fry the onions and garlic until golden brown. When they are cooked, slowly add a bottle of beer, bring to a boil and sauté for a few minutes until it reduces. Remove and set aside.
Brush or rinse the mushrooms clean and thinly slice them. In a frying pan, heat some butter until hot and fry mushrooms for about 10 minutes. Remove and set aside. Divide the mushrooms in half and keep half aside separately to add back into soup after you blended the soup.
In a large stockpot, add the vegetable stock, half of the fried mushrooms, fried onions, potatoes, bay leaf and thyme sprigs and bring to a boil and simmer for about 20 minutes, until the potatoes are cooked.
Remove the bay leaf and thyme sprigs. Using a stick blender or immersion blender, blend the mushroom soup until you have a smooth consistency. Add the remaining mushrooms back into the soup. Optional: can mix throughout a quarter cup of whipping cream.
Season with fresh thyme, salt and pepper to taste. Serve with a crusty loaf of bread.