A very large all-you-can-eat restaurant located right next to the Porte de Pantin metro station (line 5), not far from the Zénith concert hall. There's a wide variety of dishes on offer: Chinese, wok, grilled meats, and Japanese. Quite rare in Paris!
I found the place clean, the service pleasant, and the overall price very reasonable (22 euros in the evening).
If you're in the area, I recommend it :-)