For the sour meat, cut the pork belly into thick slices and place in a large cooking pot.
Peel the onions, cut them into thick rings and spread them on the slices of meat. Sprinkle with a little salt.
Put 750-800 ml of water in a pot and stir in sugar with vinegar. Pour the vinegar-sugar-water over the meat and slowly bring the whole thing to a boil. Skim off any foam with a slotted spoon.
Add the spices (crush the juniper berries) and let it simmer at low temperature, uncovered, for about 3 hours.
Lift out the meat slices and place in a baking dish. Add aquavit to the cooking stock and pour over the meat. Allow to cool.
Place the sour meat from Mecklenburg-Vorpommern in the refrigerator overnight to gel.