In a casserole, cover cubes of celery root and potatoes with water. Bring to a boil and cook until tender.
In a pan, melt 15 ml (1 tablespoon) of butter to medium heat. Cook the cutlets for 2 minutes on each side. Place the cutlets on a plate and cover with aluminum paper. Set aside in a warm oven.
In the same pan, add 15 ml (1 tablespoon) of butter and cook leeks at low heat for 8 to 10 minutes. Add honey, apple cider vinegar and sage. Cook for 1 minute.
When the potato cubes and celery root are cooked, drain. With a pestle, set cubes into puree. Add butter, cheese, cider vinegar. Mix well. Salt and pepper up to taste. On a serving plate, lay a portion of celery rave puree, then cutlets and garnish with leeks. Pepper.