Looking for a vegetarian Thanksgiving gravy recipe? Then try this rich, earthy gravy, which can be made with fresh shiitakes as well as portobellos. Leave the mushroom pieces in for a chunky-style sauce or strain them out for a velvety consistency.
Heat the oil in a medium-sized saucepan over medium heat. Add the onion and garlic. Cook, stirring often, until softened, about 5 minutes. Add the mushrooms and cook, stirring often, until they begin to release their juices, about 10 minutes.
Add the broth, tamari, thyme, and sage, and simmer for 10 minutes. Mix the cornstarch and water in a small bowl. Stir into the sauce and simmer, stirring often, until slightly thickened, about 10 more minutes. Season with pepper, to taste. (If you prefer a smooth gravy, pass it through a fine sieve and discard the mushrooms and onions.) Serve hot.