Drain and rinse the chickpeas thoroughly, then pat them dry with a paper towel.
Place the chickpeas, parsley, garlic, hemp hearts, cumin, coriander, salt, and pepper into a food processor.
Pulse the mixture until it forms a coarse, uniform meal that holds together when pressed, being careful not to over-process into a paste.
Divide the mixture and shape into 4 to 5 small, even patties.
Heat the olive oil in a non-stick skillet over medium heat.
Place the patties in the skillet and cook for 3 to 4 minutes per side until they are golden brown and crispy.
While the falafel cooks, whisk together the Greek yogurt, tahini, and lemon juice in a small bowl until the sauce is smooth.
Serve the warm falafel patties immediately, topped with a generous dollop of the tahini yogurt sauce.