Gristly means rubbery or full of cartilage. The hardest part of your trip to rural China might be graciously accepting and attempting to chew the gristly meat your hosts offer you.
The Old English word that spawned gristly is gristle, literally meaning "cartilage." When meat in particular is hard to chew, it's gristly. This adjective sounds like grisly (no t), which describes something that is horrifying. Although it can also be horrifying, save gristly to describe that chewy mystery meat you try and choke down to be polite.