Heat a large skillet over medium heat. Once hot, add 1 tablespoon of vegan butter. Once melted, add the onion and mushroom and sauté until soft and fragrant, about 10 minutes.
Transfer the onions and mushrooms to a high-powered blender. Add in the vegetable broth and soy sauce to a high speed blender and blend until completely smooth. Set aside.
Back in the same skillet, add half a cup of vegan butter. Once melted, add in gluten free flour and spices and whisk together with the butter until a paste forms.
Next, slowly pour the blended mushroom mixture into the skillet with the roux as you whisk constantly. Make sure to whisk as you pour or clumps will likely form.
Allow gravy to simmer for 20 minutes, then serve immediately.
Notes
Depending on the gluten free flour you use, it may have a couple of lumps. Lumps should dissipate once the gravy simmers.
You can use all purpose flour if you are not gluten free!