I just watched the Dipuranja Youtube Onion Bhaji video.
http://www.youtube.com/user/dipuraja1#p/a/u/0/hFeRuAT_gJIIt was a very interesting watch and although I don't think the results from his effort looked very good, it does reinforce a couple of my thoughts from my Bhaji experiments. Firstly (and I appreciate it's only based on this one video) it would appear they dont premarinate the onions in salt and spices before they are made. I found this made the onion too soft so you end up with a very smooth ball and a sludgy middle. The idea of keeping everything very loose to maximize the internal surface areas in contact with the hot oil makes sense. Almost all BIR OB's are a bit spiky with onion jutting out everywhere, you definitely lose this with the premarinading so for me, that's out moving forwards.
The use of an egg as a binder isn't a new idea but is one I discounted a while ago in favour of standard water based batter. I'll revisit now as it might be the only way to get the onions sticky enough for a light coating of flour.
The lentils are also something I haven't tried before so I'll give them a go.
I'd never really considered it might be food colouring giving the internal colouring, I'll be buying some of that today.
Finally I can't tell you how pleased I was to see the potato going in too. That is now 4 out of 4 Indian chefs I have heard say this should be added. CA - it's time to accept the truth!