A day before you plan to cook the falafel balls, put the chickpeas in a large bowl and cover them by a couple of inches with water. Stir in the baking soda. Cover and let sit for 12 – 24 hours. If it sits for more than 12 hours, change the water once.
Drain and dry the chickpeas. Place them in the food processor with the green onions, garlic, parsley, cilantro, flax meal, cumin, salt, coriander, pepper, and baking powder. Pulse in long pulses several times until the mixture has the consistency of a coarse paste, scraping down the sides of the bowl often.
Put the mixture into a bowl, stir with a fork, and remove any large pieces of chickpeas that may not have been processed. Cover and refrigerate for 30 – 60 minutes.
Preheat the air fryer to 375 degrees.
Form the falafel mixture into balls using about 2 tablespoons per ball.
Spray the air fryer basket with oil spray, place a layer of balls into the basket, and lightly spray with more oil spray. Air fry for 6 minutes. Flip them over and air fry for another 6 minutes or until browned and crisp.