Most winter greens are sold in bunches. One exception is escarole, which grows in a lettuce-like head. It has tender, pale green leaves that are slightly bitter tasting. As more layers of the head are peeled back, the leaves become milder in flavour. Together, the leafy greens, earthy beans, and tasty meatballs elevate this soup to a point where you’ll want to make it a regular part of your winter menu. If desired, you can use kale or mustard greens in lieu of escarole and lean ground chicken instead of turkey.