Roast all the ingredients one at a time (except the turmeric), until they are a couple of shades darker and aromatic. Roast the garlic and the onion until dark spots appear, but don't let them burn.
Remove everything to a dish to cool, and then place in a blender. Blend into a coarse powder. I sometimes add some coconut milk, blend the masala into a paste and then freeze it, but you can skip that because we are trying to cut out fats from our diet.
Recipe by Holy Cow! at http://holycowvegan.net/2012/01/my-dads-not-mutton-mushroom-curry-fat.html