Salads, especially those of the mason jar variety [1], might win out in a popularity contest, but soup is just as good a brown-bag lunch option. Most recipes [2] reheat well, are hearty without inducing a food coma, and are easy to pack, provided you follow a couple of simple guidelines:

• Don't pack your soup in any old resealable container. The potential for messy spills in your bag is too high. Do bring soup to work in a pint or half-liter mason jar or a container with a locking snap-on lid [3].
• Do bring garnish items like fresh herbs, grated cheese, or croutons in a separate container, adding them to the soup after reheating so as to maintain their fresh flavor and texture.
• Don't reheat your soup in one go, as it will heat unevenly, leaving gummy, overcooked edges. Instead, pour the soup into a microwave-safe bowl and heat in one-minute intervals, stirring between, until hot.