Pierce the pork several times with a sharp thin knife and place in a large bowl.
In a blender, combine the garlic, onion, 250ml cider and salt and pepper to taste. Blend well, pour over the pork, and cover the bowl with cling wrap. Marinate in the fridge at least 6 hours, or overnight.
Remove the pork from the fridge and allow to come up to room temperature, then transfer to a roasting tin. Reserve the marinade.
Preheat the oven to 180 degrees C.
Combine the reserved marinade with the pineapple juice. Insert the almonds and prunes into the slits in the pork and inject the remaining cider into the slits with a baster. Rub the pork with the lard and top with the pineapple slices.
Cover the pork with foil and bake for 5-6 hours. Baste with reserved juices several times while baking. Remove the foil for the last 30 minutes of roasting.