Quotei'm afraid i've no intention of chasing my tail.
Me neither, why consider bhaji/old /near rancid/burned oil as important, when a wealth of information on here, ie video footage from named restaurants, chefs knowledge, incredibly "experienced amateurs", & people who have actually worked in bir kitchens, prove otherwise.

The Zaal info, told me:
The gravy recipe's on cr0 are good to go!
Msg was not added!
Ground spice can be cooked for longer than I was led to believe!
Cooking a dish at home will take slightly longer than the time shown in the professional kitchen videos
The frying stage up to the gravy,has to be done correctly, ie rawness removed
It was all the information I needed to confirm, that everything I need is here & always has been!
Fresh oil / GG or Garlic only /spice/methi/salt/ tomato paste(crucial these are fried properly) / base gravy
bir aroma here - Hard bit over

The addition of mixed pickle, Banjarra onion paste, any other onion paste,'Magic Sauce', masala / Jhal paste, extra garlic/ginger, tikka meat, chilli sauce, mango chutney, cream, spinach........... is where the complex flavours from. Apologies if this is patronising anyone, but I've never made onion bhajis in my life never mind use the leftover oil
Regards
ELW
Ps - If I found out for sure than my fav bir's used oild fryer oil rather than fresh, I'd find somewhere else to dine

other than penny pinching, there is no need for it