Melt the butter in a heavy-bottomed soup pot or dutch oven over medium heat. Add the onions and saute over medium to high heat for 3-4 minutes or until soft.
Add the mushrooms, thyme and salt to the pot and saute for 10-12 minutes until the liquid from the mushrooms as completely cooked off.
Turn the heat up to high and add the white wine. Cook for 3-4 minutes until the liquid has cooked off.
Turn the heat back down to medium and sprinkle the mushrooms with the flour. Stirring regularly, cook the flour for 2 minutes to ensure it isn't raw.
A cup at a time, stir in the stock and miso paste.
After the last cup of stock, add the coconut milk. Swap to a whisk and bring the soup up to a simmer, gently whisking. It will thicken as you whisk. Once you have your desired consistency, the soup is ready to serve.
Season with the pepper and more salt and serve.