My first time on here and this is exactly why I joined - the red sauce that comes with onion bhajis is amazing, and Ligs I think we are possibly talking about the same thing?
In Norfolk it is a thin sauce (sort of milk/single cream consistency I guess?) and a really deep red almost brown colour. The flavour is kind of sour I guess, so I always assumed it was Tamarind, bought a bottle of Maggi Tamarind sauce and it was not the same

But it always comes with Bhajis.
I'm doing a curry feast for friends at the weekend so will try to give one of these recipes a try! Chewytikka, you posted some photos of your onion bhajis with a raita and tamarind sauce I think, and I wondered what the recipe was for the tamarind sauce? It looked like a similar consistency and I wondered if it was the same but at the BIR they add in some food colouring?

Anyway, thanks for all the information, you guys are legends! ;D