Paumanok Vineyards’ chenin blanc is one of the great mysteries of the North Fork wine world. Why? Because despite all the success the Massoud family — which owns the Aquebogue vineyard — has had with it, they remain the only Long Island winery to grow or make it. By all accounts, it’s not tricky to work with — at least no more so than any other grape in our sometimes challenging maritime climate. It ripens and performs consistently in the vineyard and doesn’t require unique or special treatment or protocols. Paumanok’s winemakers — first Charles Massoud and now his son Kareem…