Edit: This place is now a different restaurant.
A few months ago, a stand of floral arrangements on Xiaojiahe street heralded a newly opened jiaozi joint. It's a narrow little place, with two rows of benches along the sides of the room. The efficient servers might greet you with, "Shenme xianr?" - "What filling?". If they have made white fungus soup (银耳汤）, they will let you know (and you should get some).
My first order there was a liang of egg jiaozi (鸡蛋) and one liang of suancai (pickled cabbage mixed with meat) jiaozi (酸菜）. The egg jiaozi, usually my favourite kind, was meh. The suancai jiaozi was tender, fragrant, and had a great balance of tart suancai and rich ground pork. I found myself coming back to the shop, intending to try different things but getting stuck on the suancai jiaozi. The shiitake mushroom and pork jiaozi (香菇) are also very good. Jiaozi fixings:
They also have a short menu of Dongbei (Northeast) favourites, such as battered pork slices in sweet and sour sauce (锅暴肉). Their version of this dish is too heavily battered for me, but those who love Westernized Chinese food would probably enjoy it. There is also an oily but melt-in-your-mouth version of 'triple earthy freshness' (地三鲜）; a stir fry of potatoes, peppers, and eggplant.
Address: Xiaojiahe street. Close to Grandma Jin's The place is a little expensive but you can still get out of there for Y10 per person. If you order the Dongbei dishes it's Y15-20 per person.