Blanch cabbage leaves in boiling water and cut away any tough sections from their bases.
Cut white roots from spring onions and finely chop 4 white heads. Slice 2 for garnish. Halve green stalks lengthwise to make strips.
Thoroughly mix well chopped spring onions and 2 tablespoons of coriander with pork and prawns. Season with pepper. Set stock to boil.
Into each cabbage leaf, place 1 tablespoon of mixture. Fold the leaf base over, then the outer edges and roll up. Carefully tie up each roll with a length of green spring onion and place parcels gently into boiling stock to cook for 6 minutes.
Lift parcels into bowls, pour a cup of stock over each and garnish with remaining sliced spring onions and coriander. Dip rolls into fish sauce when eating.
