Sauté the Aromatics: Heat olive oil and butter in a large pot or Dutch oven over medium heat. Add the chopped onion and sprinkle with sea salt. Cook for 5–7 minutes until the onion becomes soft and translucent.

Cook the Mushrooms: Add the sliced white button and cremini mushrooms to the pot. Season with black pepper and stir. Cook for 8–10 minutes, stirring occasionally, until the mushrooms release their liquid and start to brown.

Add Garlic and Wine: Stir in the grated garlic and cook for about 30 seconds until fragrant. Pour in the dry white wine, scraping up any browned bits from the bottom of the pot. Let the wine simmer for 2 minutes to cook off the alcohol.

Simmer the Soup: Add the vegetable broth, tamari, and fresh thyme leaves. Stir to combine, then bring the soup to a gentle boil. Reduce the heat to low and let it simmer uncovered for 15 minutes to allow the flavors to meld together.

Blend for Creaminess: Use an immersion blender to blend the soup directly in the pot. Blend partially for a chunky texture or fully for a smooth consistency. If you don’t have an immersion blender, transfer the soup in batches to a regular blender, blend until smooth, and return it to the pot.

Add the Cream: Stir in the heavy cream or crème fraîche for a rich, velvety finish. Taste the soup and adjust the seasoning with additional salt and pepper, if needed.

Serve and Garnish: Ladle the soup into bowls. Drizzle with a touch of olive oil and garnish with fresh parsley and thyme leaves. Serve hot with your favorite crusty bread or crackers.