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.
Your tongue can turn black if you have eaten something that has stained it. Black licorice can stain your tongue, as can chewing tobacco. If you have a black tongue, then you could have a fungus called Aspergillus niger growing on the surface of your tongue. If you have too much bacteria growing in your mouth, it could cause your tongue to appear black and hairy, according to the Mayo Clinic.