Preheat oven 160c.  Roast kumara with oil and seasoning until tender.  Heat butter and oil and cook leek, celery, garlic until soft.  Add rice and stir to coat.  Reduce heat to medium and add hot stock and wine, only ¼ C at a time, allowing to absorb each time, for 18-20 mins until rice creamy but firm to bite.  Stir in kumara, parsley, cheese.