By nestling your lamb roast on a layer of thickly sliced onions,tomatoes, mushrooms and a sprinkling of fresh rosemary you can make a lovely additive free, delicious gravy! Manufacturers sure know how to sneak those nasties into everything! By making your own gravy, you know exactly what you are eating, minus those artificial flavours and colours.
I just drain the liquid from the roast, remove most of the fat, then slowly add the liquid to some flour. Being careful to whisk the gravy mixture, as to not form any lumps. Cook over a low heat, stirring constantly until it thickens to your desired consistency. Salt and pepper to taste.