Soak the chickpeas. Add the chickpeas into a large bowl and cover with water. (The chickpeas will double or triple in volume, so use more water than you think you will need). Soak the chickpeas for 24 hours at room temperature. Then drain the chickpeas, rinse under cold running water, and use as instructed.
Preheat the oven. Arrange a rack in the middle of the oven. Heat the oven to 400ºF/204ºC.
Process all the ingredients. Add all the soaked chickpeas, parsley, cilantro, onion, garlic, chickpea flour, cumin, coriander, baking powder, and salt into the bowl of a food processor and pulse until well combined, but not puréed. The texture of the chickpeas should be uneven and coarse, with some slightly larger pieces still visible. If the mixture is too wet, add a little bit more chickpea flour, 1 Tbsp./5.7 g at a time. If it's too dry and crumbly, pulse it a little bit more.
Season. Taste and adjust the flavor as needed, adding more salt for saltiness, garlic for pungency, cumin for earthiness, and coriander for a citrusy-nutty flavor.
Refrigerate the falafel mixture. Transfer the falafel mixture into a bowl, cover, and refrigerate for at least 30 minutes.
Form the falafel mixture into patties. Scoop out about 2 tablespoons of the mixture. Using your hands, gently form the mixture into 0.5-inch/1.3-cm thick patties. Avoid packing the patties too tightly or they will come out tough and dense. Repeat until all the falafel mixture is used up.
Brush with oil. Right before baking, brush/spray each falafel with a little bit of olive oil.
Bake. Arrange the falafel patties onto a greased baking sheet and bake until crispy and golden brown, for 25-30 minutes, flipping halfway through baking.
Serve immediately, while still warm and crispy over greens or in a warmed pita bread with hummus, tomatoes, and shredded lettuce.
Store. Leftover falafel keeps well in an airtight container in the refrigerator for up to 5 days, though best when fresh. For longer term storage, freeze uncooked pre-shaped falafel in a single layer. Once firm, transfer the falafel into a freezer-safe bag or a container and place it back into the freezer for up to 3 months. (You can freeze cooked falafel as well, but it’s never quite as good).
Reheat in a 400ºF/204ºC oven until heated through and crispy again, for about 5 minutes. If reheating frozen (uncooked) falafel, transfer the falafel into the refrigerator 24 hours before baking to thaw. Once thawed, follow the instructions for baking above.