Personally I like the cabbage in the base. It bulks it up and definitely adds something that suits my taste buds, but it also MUST have green pepper and carrot in there too.
I recently tried the Little India gravy, kindly filmed and added by CBM, and it was good. I think a few tweeks to add cabbage and green pepper would make it better (for me personally).
Never thought of adding swede, but here in Perth, swede costs more per kilo than chicken breast.

Cabbage is cheap and plentiful, so that suits me.

I've also tried boiling up a chicken carcass in the base, but can't say I noticed too much difference in the finished curry.
Also, I unwittingly served up a mushroom bhajee to one of our veggie friends, and it was only a few days later that I realised it was the chicken carcass base gravy that I'd used............OOPS!! I still haven't told her!!
