Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Rinse and thoroughly pat the chickpeas dry with a paper towel to ensure a crispy texture.
In a food processor, combine the chickpeas, egg whites, hemp hearts, parsley, cilantro, garlic, cumin, salt, and pepper.
Pulse the mixture until it forms a coarse, uniform paste, being careful not to over-process into a smooth purée.
Form the mixture into 4 or 5 small patties and place them on the prepared baking sheet.
Bake for 18-20 minutes, flipping the patties halfway through, until they are golden brown and firm to the touch.
While the falafel bakes, prepare the sauce by whisking the Greek yogurt, tahini, and lemon juice in a small bowl until creamy.
Slice the whole wheat pita in half and warm it slightly in the oven or a toaster.
Stuff the pita halves with the baked falafel, diced cucumber, and diced tomato.
Drizzle the lemon-tahini yogurt sauce over the filling and serve immediately.