This was, coincidentally, the day it snowed, about which I was PRETTY EXCITED, so had spent two hours wandering around Ditan, taking photos and playing in the snow.

So I wandered over to Dongsishitiao and in to Sunao, covered in melting snow and wearing a hoodie under my coat, only to discover that Sunao was not a casual tea house, as I had expected, but a very fancy restaurant. The menu was all in Chinese characters with minimal pictures, and the staff were beautifully dressed (no English speaking) and the settings were awesome, and I sat down, intimidated.
The front of house asked me twice if I could read (I don't think he believed me). The waitress was super excited to see me reading, but when I ordered a salad and then a tofu dish, she redirected me to another dish. I wasn't clear on all the characters, but I thought I'd give it a go, see what I ended up with.

I ended up with a mushroom pepper steak, which, it's been a while. And it was unexpected. But it was excellent! Not too chewy, slightly hot mushroomy flavour, presented beautifully and served with roasted potatoes and carrots. Totally unexpected but an interesting experience.
I would definitely not go by myself again, but I would consider a group (booked, and well-dressed) visit.
Sunao
Ground Floor, East Side
Nanxingcang Business Building
Dongsishitiao
Dongcheng
Get there on line 2, exit C. Little step up to enter, well-lit but I was only there in the daytime.