Soak the dried chickpeas in a large bowl covered with water for 24 hours. Drain them thoroughly to remove excess moisture.
In a food processor, combine the soaked chickpeas, onion, parsley, cilantro, salt, garlic, cumin, and coriander. Process until blended but still slightly coarse.
Transfer the mixture to a bowl, then mix in the chickpea flour and baking powder.
Form the mixture into balls about the size of a heaping tablespoon, flatten them slightly. Place on a parchment-lined tray.
Refrigerate for about an hour to firm up.
Heat vegetable oil in a large skillet over medium heat.
Carefully add the falafel balls to the hot oil, cooking for 30-60 seconds on one side until golden brown, then flip and cook for another 30 seconds.
Remove falafel from the oil and place on a paper towel-lined tray to soak up excess oil.
Serve in pita bread with lettuce, tomato, and onion, or on a side platter with rice and salad.