In a 3 litre saucepan, combine the oil, potatoes, onion, bell peppers, ham and celery. Cook over low heat 10 minutes stirring occasionally. Add the hominy, chilies, flour, thyme, salt and pepper. Gradually stir in the milk, and bring to a boil. Reduce the heat, simmer, covered, for 30 to 40 minutes or until soup is thickened and potatoes are tender. ----