Chewy, springy wheat protein with little taste of its own, so it soaks up sauce. It is sold as hollow fried balls (油面筋), as steamed rolls, or as spongy 烤麸, and street stalls grill it on skewers.
Vegetarian restaurants often use seitan as a meat substitute.
Tips
culture
面筋 is the chewy protein left after washing starch out of wheat dough. It's a staple in Buddhist vegetarian cooking and predates Western 'seitan' by centuries.