1.Heat oil in a large saucepan on the stove over medium heat for 1 minute. Add onion, garlic and ginger and stir with a wooden spoon for about 5 minutes or until the onion is soft.
2.Add stock, water and both corns to the pan. Place lid on pan, turn heat to high and bring to the boil.
3.Keep the green parts of green onion in a small bowl; add the white parts to the pan. Reduce the heat to medium-low. Simmer, uncovered, for 5 minutes.
4.Carefully break the noodles in half and add to the pan. Simmer, uncovered, for about 2 minutes. Stir to separate the noodles.
5.Add chicken to pan and simmer, uncovered, about 1 minute or until the chicken is cooked. (Add extra soy sauce to taste, if needed.)
6.Stir in the spinach. Divide soup into four serving bowls. Sprinkle with remaining green onion.