In any wide container (bowl, loaf pan, Tupperware, etc.) soak the dried tofu skin in room-temperature water according to package instructions, around 1 hour or until soft and tearable. (Denser types like "sticks" may take up to 6 hours, so be sure to check beforehand.)
In a large bowl, scrub the meat with cold water and a handful of flour to clean it of any sliminess/gunk. Rinse thoroughly, rinsing 2-3 times until the water runs clear of blood. Drain.
Blanch the cleaned meat by adding it to a pot of cold water over medium-high heat with the smashed ginger, scallion knot and splash of liaojiu. Bring to a boil for 5 minutes, or until most of the scum has been forced out, skimming foam as it appears.Meanwhile, combine the star anise, cassia bark, sand ginger, cloves, bay leaf, dried chili and whole red huajiao in a small bowl. Rinse gently in one change of water and set aside to soak in just enough clean water to cover.
Retrieve the trotters with a strainer into a bowl with 4-5 cups of hot water prepared ahead. Do not use cold water, or it will tighten the meat. Scrub the trotters of all the scum underwater, then rinse under hot water and drain into a clean bowl. Set aside.