Dissolve the stock cubes in the boiling water in a saucepan over a medium heat. Add the sweetcorn and garlic and simmer for 3 minutes.
Mix the cornflour with 3 tablespoons of cold water to a smooth paste. Stir it into the soup and simmer for 1 minute until slightly thickened.
Stir the soup in one direction so it is moving, then slowly pour in the beaten eggs in a thin stream while stirring gently. The egg will set in soft ribbons.
Add the soy sauce and a good grind of white or black pepper. Do not let it boil. Ladle into bowls and scatter with the sliced spring onions.