1/4cupCornstarchThis is approximate. You might use more or less depending on how thick you want the gravy.
In a saucepan over medium low heat, saute pureed onion, celery and carrot in the olive oil. Saute until onions & celery are translucent and carrots are very soft.
Add half the cornstarch to the pan, whisking constantly until the mixture forms a smooth paste.
Add the vegetable broth and soy sauce. Whisk until smooth. Turn heat up to medium.
Add nutritional yeast, sage, black pepper, celery salt and fennel seed. Whisk constantly until smooth.
Continue whisking. Bring the gravy to a boil, then lower heat to simmer. Whisk frequently.
Simmer until the gravy thickens. If needed add additional cornstarch (blended with a small amount of water) and whisk until smooth. Stir in parsley. Continue simmering for another 5 or 10 minutes, whisking frequently.
Taste test. Add salt if needed. Add any other spices to taste. The gravy is ready once it tastes good to you and is as thick as you want it.