Blustering snow and icy rains found us craving a hearty soup this week.   Gazing down the steep cobblestone hills winding down from our house, we opted for caution, and a pantry raid, in favor of driving.  For our winter-storm-fare, we dunked homemade sourdough bread in aromatic bowls of French Cabbage Soup, and dreamed of beaches!   Our recipe for French Cabbage Soup, Garbure Gasconne, is a modified version of this delicious cabbage soup from the French region of Gascony.  This soup smartly employs steaming and simmering techniques to gently extract the delicate flavors from winter root vegetables.  French Cabbage Soup is a warming vegetable soup with a depth of flavor that far exceeds its humble ingredients.