Heat the oil in a large pan over medium-high heat. Add the onion and celery and cook, stirring frequently for 5 minutes. Add the diced potatoes. Stir lightly then reduce the heat to low, cover the pan, and let cook for 10 minutes. Stir in the parsley and savory. Mix together the flour and milk until it forms a smooth paste. Add the paste to the pan and stir well. While stirring, slowly add the broth and continue to stir until the flour paste is completely blended in. Increase the heat to medium-high and bring the chowder to a boil. Reduce the heat to a simmer and let cook until the potatoes are tender. Add the chicken and corn and season to taste with salt and pepper. Cook for 5 more minutes or until the soup is heated through. Serve hot.