Redwood Foods versions of these are sold in Holland and Barrett, Asda and wholefoods shops. Gravy granules. Just because you're feeding a vegetarian or vegan doesn't mean they have to have 'vegetarian' gravy (you know, the thin watery stuff that looks like a dissolved vegetable stock cube).
If your tongue is stained black or dark brown it may be caused by medications and certain foods/drinks. Drinking several cups of coffee or tea per day may stain the tongue; some people who supplement with green drinks containing chlorophyll may notice a very green tongue.
Signs and symptoms of black hairy tongue include a furry appearance, altered taste, bad breath, a gagging or tickling sensation and brown, black, tan green or yellow discoloration of the tongue. Poor oral hygiene or using medications that contain bismuth can sometimes cause black hairy tongue as well.