Pet nat — shorthand for Pétillant Naturel — wines are all the rage these days, particularly in New York City. These are lightly sparkling wines made in a style that, while new to the New York wine industry, is far from trendy or new. In fact, the method is as rustic and old as the wines are fun to drink. Unlike sparkling wines made using methode champenoise (as with Champagne), where yeast and sugar are added to a fully fermented base wine for a secondary carbonation in the bottle, pet nat is made via méthode ancestral, where the wine is bottled before primary fermentation —…