Add the onion and garlic cloves to the bowl of a food processor and pulse just until finely chopped; remove the mixture to a bowl and set it aside.
To the food processor, add the chickpeas, parsley, cilantro, salt, chili powder, and cumin and pulse until blended but not pureed.
Return the onion mixture to the food processor, along with the baking powder and half the flour; pulse until the mixture begins to form a ball and is not sticky. Add remaining flour, as needed.
Transfer the falafel mixture back to the bowl, cover, and refrigerate it for at least 1 hour.
Once chilled, use a 2 tablespoon scoop and form the mixture into small, flattened balls.
Heat 1-2 tablespoons of oil a large skillet over medium heat. Once hot, add the falafel one by one, browning them for 2-3 minutes per side; allow to drain on a paper towel or cooling rack line with paper towel. Repeat with remaining oil and falafel, working in batches. Serve warm.