Tayyabs in between Aldgate East and Whitechapel. By far an away the best place in London for it... and just round the corner Lahore Kebab House is another strong option, but not a patch on Tayyabs imo. It's chaotic, the staff are rude and indifferent, but the food is rather good.
http://www.timeout.com/london/restaurants/tayyabs
http://www.theguardian.com/lifeandstyle/2005/may/08/foodanddrink.shopping
You see this is one such example.
Tayyabs is at best middling to fairly good, but in the last 12 months I have been there 3 or 4 times with people from London who hear my midlands twang and think I will want a curry. They are of course 100% correct and I've not had bad food there, but places like Tayyabs are 10 a penny in Brum for example.