One of the branches of this dosa chain; been years on my list to try.
The potato and vegetable filling was a little sloppily spread within the special onion rava masala dosa, but it was very hard to argue with the flavour, lightly but surely spiced, no traces of greasiness, the potato soft but not grainy (compare with the texture mashed potatoes at fancier places that charge 5-10x!). Basic unfussy chutneys -- coconut, red (tomato?), green (chilli/coriander if I'm right) -- and a medium thick sambhar, all synergising nicely and naturally with the dosa. Texture of the dosa itself was great -- crisp, ever so slightly sticky, and delicately thin. £3 for a good sized serving.
Incidentally, noticed that Saravana Bhavan has a branch nearby; probably old news to many. How does it compare with the East Ham branch?
P.S. Anyone been to Diana, the Afghan restaurant nearby?