smoked pork knuckle
Cured and smoked lower leg of pork, with rind and bone, cooked slowly to give broths smoke and body.
In German-speaking countries it is sold at butchers and often vacuum-packed in supermarkets; in English-speaking countries look for smoked ham hock at butchers, larger supermarkets or Eastern European shops. Make sure it is smoked and not merely cured, since the smoke carries the flavour.
Substitute:
A piece of smoked pork belly or smoked ribs gives the smoke but less gelatine, so the broth stays thinner; simmering a pig's trotter alongside makes up for it.