If you have only ground spices rather than whole berries, reduce to 1 teaspoon each. Likewise, one teaspoon of ground cinnamon is probably sufficient.
For two hungry people:
Chop the onion in half lengthways, then cut each half into about 6 wedges. Peel the carrot, then cut into chunky half-barrels. Peel the celeriac thickly (use a knife not a peeler) and dice coarsely to get chunks about the same size as the carrot. Peel the garlic and chop roughly. Heat the oil in a large saucepan which has a well-fitting lid, or a casserole. It must be large enough that the lamb shanks can be laid down. Briefly fry the vegetables and garlic, sprinkling with salt to prevent browning, until the onion is softening. Remove the vegetables from the pan. Turn up the heat and add the lamb shanks. Brown on each side, about 3 minutes each. Return the vegetables to the saucepan. Roughly bash the allspice and juniper berries up in a pestle and mortar (or in a plastic bag with can or similar), then throw in the pan with the cinnamon sticks broken in half, the bay leaves and the grated nutmeg. Stir round, add the wine and water or stock and the sugar, then bring to the boil. Turn the heat down, cover with the lid and simmer gently for at least 1 hour, ideally 1 1/2 - 2 hours. If the lid is not tightly fitting and the liquid is evaporating quickly just top it up from a hot kettle as necessary. Towards the end of the cooking time taste the liquor and season with salt and pepper. Cook for about 10 minutes with the lid off to allow the sauce to reduce a bit. Serve with fresh green vegetables.