String celery and slice thinly. Heat oil in a saucepan and add celery, carrot, pinch of sea salt and onion. Cook together for 5 minutes on a medium heat.
Add water, corn cobs, kombu, bay leaf and bring to a boil. Turn down heat and simmer for 30 minutes. Remove kombu, bay leaf, corn cobs and then remove the kernels. Discard kombu, bay leaf and corn cobs, and set kernels aside.
Place contents of saucepan into blender and blend until smooth. Place a little soup in a bowl with the miso to form a paste. Add back to soup along with the kernels. Stir through. Let stand for 2 minutes and serve garnished with parsley.