An aperitif should whet the appetite, not extinguish it. It should be light-bodied, low in alcohol, and dry -- a prelude to the meal, or, better yet, a libationary preview. The Armagnac-based aperitifs at D'Artagnan are as thoroughly Gascon as the apple croustade and the duck-enriched garbure. The pousse rapiere blends Armagnac liqueur with sparkling wine; according to co-owner Ariane Daguin, it's the first thing you're offered when you enter a Gascon house. Equally authentic is the vin d'orange, a white Cotes de Gascogne infused with fresh orange, orange zest, sugar, and Armagnac blanc, the potent indigenous eau de vie. "All the grandmothers make it," says Daguin, who monitored the maturation of her homemade wine sip by citric sip. It's a tough job, but in the absence of any Gascon grandmothers, someone's got to do it.