Preheat oven to 400°F (200°C) and line a baking sheet with parchment paper.
Combine soaked chickpeas, hemp hearts, parsley, cilantro, onion, garlic, cumin, coriander, salt, and cayenne in a food processor.
Pulse until the mixture is finely minced but not pureed, maintaining a coarse texture.
Transfer the mixture to a bowl and fold in the baking powder.
Form the mixture into 16 uniform balls or slightly flattened patties, approximately 2 tablespoons each.
Place on the prepared baking sheet and brush the tops generously with olive oil.
Bake for 25 to 30 minutes, flipping the falafel halfway through, until the exterior is golden and crisp.
In a separate bowl, whisk together the tahini paste, lemon juice, and warm water until a smooth sauce forms.
Serve the baked falafel immediately with the tahini sauce.