Scrub and trim the vegetables, then slice them into long ribbons, using a vegetable peeler for the Carrots and Parsnips, a sharp knife for the Leeks. In an 8" or 9" skillet, toast the cardamom in the oil for 1 to 2 minutes over low heat, then add the vegetables, stirring to coat them with oil. Cover and cook very slowly for about 20 minutes, stirring from time to time, until the vegetables are soft and somewhat caramelized. Add salt and pepper to taste. Serves 4 to 6.