Im supposing you could make up your own stock by boiling a few herbs, a carrot, potato and other veg ifywim? I make my own stock in general and dont put salt in and just boil 'leftovers' from when i cook, I keep it all in the freezer til i need to make stock, its stuff like the odd chunk of potato or carrot, celery, a garlic or 2, ginger, broccoli stalk, honestly the list goes on!