Heat the oil in a pan. Sauté with the chopped vegetables, ginger and garlic. When it is slightly done add Soya sauce and salt. Add the spinach, just few minutes before removing from fire.
Boil the vegetable stock in a vessel. Add the sautéed mixture into the boiling stock. Mix the corn flour in some water and add it into the stock. Let it boil for a few minutes. When it is boiled add sugar and ajinomoto. Before serving add pepper to the sauce.