In the London district of Southwark, there stands a massive emporium of eating; a world-famous landmark, a bounty of gourmet delights since the 19th century known as Borough Market. Stalls piled high as far as the eye can see with plump, pink radishes; brilliant emerald-colored lettuce; periwinkle carrots; fragrant, golden mushrooms; soil-dusted beets, hearty gourds — and that’s just one lone produce stand.