1In a mortar, grind the juniper berries, fennel seeds, caraway seeds, salt, and pepper into a fine powder.
2Score the skin of the pork knuckle with a knife and brush the meat and skin with vinegar.
3Make small slits in the meat and insert the garlic cloves, then rub the surface with oil and the prepared spice rub.
4Insert metal skewers through the pork to keep it upright, and refrigerate overnight.
5Arrange the carrots, onions, garlic bulb, bay leaves, and extra juniper berries in a roasting pan. Pour in the dark beer and chicken broth.
6Place the pork on a roasting rack over the vegetable mixture and roast in the oven for 130 minutes.
7Remove from the oven, brush the skin with more vinegar, and return to a hot oven for 30 minutes to crisp the skin.
8Remove the pork and let it rest.
9Strain the pan juices into a saucepan and whisk in a mixture of cornstarch and water. Bring to a simmer, season with salt and sugar, and simmer until thickened to make the beer gravy.