Add olive oil over medium heat to a large heavy bottom skillet, then add the sliced mushrooms, add salt and sauté the mushrooms until golden brown. The more you sauté the mushrooms the tastier your sauce will be. Add the mushrooms in batches so the skillet won’t be too full, this makes the mushrooms brown faster.
Remove the mushrooms, add the onions, and sauté until golden. Add the mushrooms back to the skillet, add garlic, and sauté for 1 minute, add the balsamic vinegar, add the thyme and red wine, stir to combine, and allow the red wine to reduce until you see almost no liquid in the skillet.
Add the veggie broth, allow the sauce to cook for about 6-7 minutes, add more broth if necessary. Add the cornstarch slurry, stir until all is incorporated, then add the vegan cream, and last, a couple of cubes of vegan butter
Serve it over rice, fries, vegan steaks, mashed potatoes, pasta, meatless balls, etc