Heat 2 cups water with salt in a non stick wok. Pour 2 cups water in a bowl and add ice cubes.
Add spinach leaves to the boiling water and let it remain for 2 minutes. Remove them from the hot water and add to the icy water.
Heat oil in another non stick wok, add celery and garlic and toss. Add corn kernels and 4 cups water and let it come to a boil.
Chop blanched spinach in a processor. Add cornflour mixture to the wok and cook till the mixture thickens.