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.
When consumed at a high rate over a long period, acidic foods can cause a discoloration of the tongue. The normally pink tissue of the tongue can turn a bright red. In some cases, there may also be pain or irritation. Ceasing to eat acidic foods often causes the tongue's color to return to normal.