Put a little water in a pot and add the onions and the garlic. Soften for about 7-8 minutes. Add more water if the water evaporates.
Add the herbs and stir.
Pour the stock into the pot and keep 4 tablespoons back. Add the cornflour to this remaining stock and stir until it's smooth. Pour this mixture into the pot, stirring all the time to ensure the gravy doesn't become lumpy.
Add the Worcestershire sauce and stir for a few minutes while the sauce thickens. As soon as it reaches your perfect consistency, remove it from the heat and put it into a gravy boat, or pour over your falafels or nut roast.