Street Food
When looking for something to eat I suggest you try some street food. Vendors stand on street corners or side streets and sell food that is usually like a wrap with either chicken or vegetables. Don't let the shabby stands fool you. This food is really quite good.
Also in Tianjin, you will notice street vendors selling candied fruit on sticks. These are a really great snack. My favorite is the candy coated orange slices.

Goubuli's Stuffed Buns
seems popular