In a food processor, combine the chickpeas, hemp hearts, egg, parsley, cilantro, garlic, cumin, coriander, salt, and pepper.
Pulse the mixture until a coarse, uniform paste forms, being careful not to over-process into a puree.
Transfer the mixture to a bowl and stir in the chickpea flour until well combined.
Divide the mixture and form into 4 small, flat patties.
Heat a non-stick skillet over medium heat and cook the patties for 4 to 5 minutes per side until they are golden brown and crispy.
In a small bowl, whisk together the Greek yogurt, tahini, and lemon juice until smooth.
Serve the warm falafel patties over the diced cucumber and drizzle generously with the lemon-tahini sauce.