Measure 2 tablespoons tzatziki into each of 4 small lidded containers and refrigerate.
Divide tabbouleh among 4 single-serving containers. Top each container with one-fourth of the greens (about 1 cup per container) and 3 falafel. Seal and refrigerate for up to 4 days. Before serving, transfer the falafel to a microwave-safe container and heat until steaming. Return to the original container and serve with tzatziki.