Cook olive oil, mushrooms, onion, salt and pepper in a saucepan over medium-high heat. Stir infrequently to allow the mushrooms to brown and become fragrant, about 10 minutes.
Stir in potato, old bay, and worchestershire. Cook for 10 minutes.
Pour in wine and scrape the bottom of the pan to deglaze.
Add in broth. Bring to a boil, then reduce the heat to medium and simmer for 10 minutes.
Whisk together milk and flour. Reduce the soup to low heat and stir in the milk. Cook for 2 minutes.
Take soup off the heat. Using an immersion blender, puree the soup to your desired texture.
Stir in vinegar.
Serve in bowls topped with shredded gruyere cheese.