Heat the plant-based butter in a large skillet or medium-sized pot over medium heat. Once the butter has been bubbling for a minute, add the mushrooms. Cook until the mushrooms are browned and tender, 7-10 minutes, stirring occasionally to ensure even cooking. Turn down the heat if the butter begins to smoke at any point.

Sprinkle the flour onto the mushrooms and stir well to form as even a distribution of the flour as possible.

Continue to cook, stirring occasionally, until the flour becomes a golden brown color (see note), about 3 minutes.

Slowly add the stock, stirring constantly in a circular motion as you do. Add the sherry and stir again.

Add the dried shiitake mushroom, if using.

Once you’ve reached a pretty even consistency, transfer a few tablespoons of the mixture to a small bowl. Add the soy sauce and miso to that bowl. Use a fork to mix them together, making sure the miso is evenly mixed and no chunks remain. Pour that mixture back into the gravy pan and stir well.

Reduce to low heat and simmer until the gravy reaches your desired consistency (see note), stirring periodically and taking care to scrape any lumps that form around the edges or bottom of the pot. Remove the shiitake mushroom pieces before serving.