It’s a bright, refreshingly cool morning in the vineyards of Domaine de Chevalier in Pessac-Léognan when the gravel soil of the namesake Graves region really starts to make its presence known. I’m in minute four of a low-level, half-squat, half-kneel position wrestling with an unbelievably prodigious Sauvignon Blanc vine. The current challenge: to wedge my…