Sülze (or Sulz in Austrian cuisine) is a type of German meat jelly or aspic, typically made with pork. The preparation of Sülze begins with simmering meat, often including parts rich in collagen like pork knuckles, ears, or even tongue, along with vegetables and spices.
The collagen from the meats creates a natural gelatin as it cools. The meat is then removed from the bones, cut into small pieces, and mixed back into the strained broth. This mixture is poured into a mold and left to cool, typically overnight. The gelatin in the broth solidifies as it cools, creating a jelly-like consistency.