I make a wonderful shortrib recipe. You cook the ribs at 450 for 45 minutes to render the fat, then add the sauce (water, brown sugar and ketchup) and cook it at 350 for about 3 1/2 hours. The ribs end up beautiful and the sauce is thick. When I made just the sauce last weekend it never thickened up. Would the fat from the meat thicken it? What can I do to make it thicker than water?