Place 2 tablespoons of oil in a pot. Add the onion and sauté over medium heat until tender. Add the celery, potatoes, carrots and stir well. Add the peas, zucchini, and corn and stir well. Season with salt and pepper. Add Knorr chicken stock cube and stir together until combined with ingredients.
Add the flour to the ingredients and stir well.
Add warm water and let boil for 30 minutes.
Add milk and let boil for another few minutes.
Serve hot and garnish with some chopped parsley.