On a brisk autumn flight from San Diego to Portland, Oregon, cookbook author and chef Jenn Louis was suffering from a particularly bad cold. Achy and exhausted, she came home to find a giant pot of chicken soup on her porch, lovingly prepared by her sister Stacy. As she gulped down three bowls, Louis felt the rich, soulful flavors improve her mood. The hearty, familiar taste made her think about the chicken soups of her own Jewish upbringing, as well as the ubiquity of chicken soup across culture, race, and…