I'll post it in here too.. I made my own very low fat gravy this afternoon.
4 mushrooms chopped finely
1 onion chopped finely
Frylights
Water
1 Oxo Cube (Beef is 5.1% fat, so juuuuusssst outside of the rules, all the others are less)
'fry' the onions and mushrooms in a few squirts of frylight until very soft, add cube and some water and boil, then blend down with hand blender. Not quite as good as the real thing, but definatly worth it for the XEn!