Singe the trotters and the pork head over an open flame, on the gas stove. Scrape any hair away with the edge of a knife, rub vigorously with corn flour and wash thoroughly.
Put the pork meat and thoroughly cleaned ears into a large pot, with water and salt. Let it simmer with water covering everything by about an inch (2 cm). Skim the stock as often as scum rises to the top. Add the vinegar and the vegetables only after the stock has stopped foaming. Simmer until the meat comes easily off the bones.
Debone the meat, cut it and place it into bowls.
Strain the stock and add the crushed garlic cloves. Check if the mix congeals by keeping one tablespoon of stock into the refrigerator for 15-20 minutes. Fill the bowls with stock and put them in the refrigerator for at least 12 hours before serving.