For the pork: In a large bowl, stir together the pork, shallots, garlic, lemon grass, corn flour, mint, coriander, fish sauce and salt and pepper.
Preheat the grill or barbecue. With oiled hands, shape the pork mixture into 3cm meatballs. Place the meatballs on an oiled rack or grill pan and sprinkle sugar over them. Grill for about 4 minutes or until done.
For the lime chilli sauce: In a small bowl, combine all the ingredients and stir well until the sugar is dissolved.
To serve: Place a meatball on a lettuce leaf, add some cucumber and pineapple and a sprig of coriander and mint. Wrap into a parcel and pour tangy lime sauce over.