Many farm women eagerly watch their gardens in spring for the first tender, strawberry-pink rhubarb stalks. And in autumn, when trees are tinted red by summer’s afterglow and the pleasing warmth of country kitchens invites baking, they pick tomatoes green to cheat Jack Frost. And to make pies! Both of these tart vegetables make excellent pie fillings. Surrounded by flaky pastry, they behave like fruits and actually rival them in flavor. For this reason they’re at home in the company of pies made with the gifts of orchards and berry patches.