With the side of a large knife, crush the piece of ginger, but keep it in one piece.
In a medium saucepan, combine the ginger, stock, soy sauce and sesame oil.
Bring to a boil, then reduce the heat to simmer for 5 minutes.
Remove the ginger piece, and discard.
Add the corn, rice, chicken and scallion.
Simmer a further 5 minutes, until warmed through.
Ladle into serving bowls.