Place pork in a 30cm x 25cm metal baking tray. Rub all over with oil. Rub salts into scored skin. Roast for 20-25 minutes or until skin starts to blister.
Reduce oven to 180C or 160C fan-forced. Pour milk around pork (be careful of steam and to not pour any milk over the skin). Add garlic, sage and seeds to milk. Roast for 1 hour.
Increase oven to 260C or 240C fan-forced. Roast for 10 minutes or until skin is blistered and puffed all over. Remove from oven. Carefully lift pork out of braising liquid and transfer to a plate. Stand loosely covered with foil for 10 minutes before carving.