Another failure of memory for me. I would have sworn that my Eureka moment for obtaining the flavour of Dhansak I was used at that time was when I tried KD's version. But I just looked at the recipe and there's no sugar in it! What?
I can only think that I tried the recipe as is with the essential lemon juice, which is in the recipe, judged it lacking in sweetness and while adding and tasting came to that Eureka moment of perfect sweet/sour balance. I still think sugar and lemon juice are all that's required. And yes, believe me, I've tried every combination of sweetner and souring agent (I wanted to say sourer but that can't be right).
I've tried most of the other recipes but it's only the base that's stuck with me as I find her use of cumin too aggressive in the curries.
I entirely agree with you Phil that this book did set us on the path to real BIR cooking. There just wasn't anything like it at the time* and certainly no learned BIR forums to chat on. I'm pretty sure this is where I learned the blitzed base technique from, which, let's face it, is absolutely fundamental to BIR style curries and, up to that point, was a secret in essence.
*I pulled out my 1988 copy of Pat Chapman's Favourite Restaurant Curries to confirm that his "Curry Masala Gravy" which, despite him accurately describing the large pot of golden coloured gravy on every BIR stove, turns out to be a paste the way he cooks it. Why did he do it that way? I guess we'll never know.