Rather embarrassingly, since we live just down the road from it, I had never head of Simplicity in Rotherhithe before a friend suggested it recently. The area is not over endowed with nice restaurants so I was pleased to find that it was really good. In particular, I thought it had a nice atmosphere, quiet and with friendly, knowledgeable staff. There's only one vegetarian option on the menu but it involved hollandaise sauce which makes it pretty awesome in my book. They do also say that they will be happy to cook you another vegetarian dish if the one on the menu is not to your taste which is a nice offer. In particular, the wine list was well chosen and we enjoyed the wine that we had.
The only slight criticism I'd make is that the portion sizes were a little odd - the crostini and olives that we ordered as a collective starter was very generous but the vegetarian mains were on the small side compared with the other mains.
Since it is only round the corner from us, I'm pretty sure we'll be back.