Hi Lorrydoo,

the base sauce could be as simple as a chicken gravy as you say. The point I was trying to make is that I think the base sauce is just added to make up the amount of finished sauce, its what is done prior to adding it that I think is a key.
I cooked a Chicken Curry tonight using a portion of Onion`s base sauce. Now, Onion`s base sauce is somewhat of a time consumer (no disrespect to Onion) but the end result is more like a curry sauce than a base sauce and it does produce a very nice curry. Stew`s base is less time consuming but I found it to be similar to Onion`s(no disrespect stew) (more curry than base/very nice curry). Darths`s base on the other hand, is simple, uses cheap ingredients,looks more like a broth than a curry and makes a large quantity. This is the sort of thing I imagine a BIR kitchen to use.
I fried some onions for at least 35Min's until they were dark brown (not burnt)then added ginger/garlic and chilli's. After a few Min's added some spices/a little chicken stock,base sauce then chicken/tomatoes. Result, very nice.
I think next curry I do I will boil some onions and blend them, then fry them until brown and see what difference it makes.
It is frustrating.

;D