I got a recipe for the base sauce... once again I don't actually have an exact spec (I just go by look/smell/taste)
It's basically:
* A metric shitload of onions (like 5 big ones)
* a big (1kg) tin of chopped tomatoes
* bunch of garlic (half a bulb)
* couple of carrots
* some fresh ginger
* Curry powder (not too much or it'll taste like ass)
* indian masala powder (as much as you want)
* cumin (some)
* coriander leaf (quite a bit)
* lemon juice (squirt or two)
* selection of chillis or chilli sauce (go easy on this 'cause you add more later).
chop onions + carrots into a deep pot; fry slightly; throw in garlic (chopped fine); fry very slightly; dump in all the tomatoes + lemon juice + about half the spices and chilli. cook forever at a simmer. several hours. it changes color to a lighter shade of orange. Throw in the rest of teh spices and chilli for the last 5 minutes (yeah, brewing beer and cooking sauces have parallels). Blend the hell out of the result until it's a puree. Remember that this sauce doesn't need to be bastard hot 'cause you can always add more Scovilles later
Bag up into half-kilo bags (which you can use to do a normal sized frying pan worth of curry).
to use, fry up some onions, brown your meat + veg, then throw in a pack of this stuff and any other sauce ingredients (most dairy works, spinach, coconut, cooked lentils, etc etc). Cook for half an hour + stuff in face with a side of rice.
Note: this is probably not traditional, but it was a close approximation of the texture + flavour of the local place in Edinburgh that I liked
