Use this mushroom stock to make Ubuntu chef Jeremy Fox's Celery Root, Persimmon, and Swiss Chard "Stuffing."
Place both mushrooms, carrot, celery root, shallots, and rosemary leaves in the bowl of a food processor; process until finely chopped.
Heat vegetable oil in a large pot over high heat. Transfer vegetable mixture to pot and reduce heat to medium. Cook vegetables, letting them "cake" in bottom of pot, about 5 minutes.
Add 12 cups water to pot. Simmer for 2 hours. Strain stock and let cool.