I've only a 5ltr pot at the moment, I made a 2.5 kg onion batch - exactly half of the more recent 5kg version.Scaling down by half doesn't work as a sauce on it's own. I've ran into this problem many times doing Ashoka & various others.Half of the 5ltr version will be oily & the cumulative effect on taste from the GG/whole spices are not there as there won't be enough in it to produce a sauce on it's own.I resisted adding any other spices/pastes as it's not designed for that.
It's not really all that different to Ashoka or taz methods, with the oil & whole spice etc. The pic of the actual Ashoka base on here
http://www.curry-recipes.co.uk/curry/index.php/topic,3199.0.html, looks as thick as the BB base. That may have been overlooked in Panpot's original thread.
In this case a small sample of a larger recipe produced a different result(on taste)
I'll post a couple of pics of the base, but they won't tell anyone anything
oil content;
If i wanted to upscale a batch of ca's gravy for example( 600gm onion/125ml oil/ 1600 water) to a 2.5 kg onion batch(which is still pretty small batch of gravy)....how much oil should i add if i add ingredients like for like?...the same amount as the BB 5k?
If i wanted to do the same to cbm's shah base(300ml oil/800gm onion), I would end up with over 900ml oil for a 2.5kg onion...or over 2.5 ltr oil for a 7kg batch..more than the original BB posted base, which he has since corrected to 1.5l from 2.
I'll make this base again when i get a bigger pot, as there may something to be learned from this approach.
Oil has long since been the source of conflict & power plays :

If someone disagrees with with my arithmetic above, i'm interested hear how to scale the ingredients properly
Regards
ELW