In a large skillet, heat 2 tablespoons of oil over medium-high heat.
Add the red onion, garlic and mushrooms and season with salt and pepper, to taste. Cook until the red onions and mushrooms are soft, about 5-10 minutes.
Add the red wine and scrape up any brown bits on the bottom of the pan with a wooden spoon.
Cook until the mixture thickens and most of the liquid is evaporated.
If desired, you may puree half of this mushroom mixture in a blender to make this gravy thick, or you may puree all, or none. Add the pureed gravy back into the skillet.
Stir in the vegetable broth, sage, thyme, and fresh rosemary.
Whisk in the gluten-free flour 1 tablespoon at a time.
Once the gravy is smooth and any lumps of flour are gone, bring the mixture to a boil, then reduce the heat to a simmer and cook for about 10 minutes or until thickened.
Remove the pan from the heat and stir in the butter (if using) until smooth. Season with salt and pepper to taste. Garnish with additional fresh herbs, if desired.
Recipe by Potluck at Oh My Veggies at https://potluck.ohmyveggies.com/savory-mushroom-herb-vegan-gluten-free-gravy/