Place chickpeas in a large bowl. Cover with water. Soak for 24 hours. The chickpeas will absorb water and double in size. Drain. Place chickpeas in a food processor. Process to a coarse paste. Transfer chickpea paste to a bowl.
To the food processor, add parsley, coriander (cilantro) leaves, spring onions (scallions), garlic cloves, onions and green chili. Grind to a smooth paste.
Add this mixture to the chickpea paste.
Add baking powder, flour, ground cumin, ground coriander and cayenne pepper (if using). Season with salt and pepper. Stir to combine.
Make small lemon sized balls out of the mixture. Place the balls in a single layer on a lined baking sheet. Refrigerate for 20 minutes.
To deep fry: heat oil in a large pan over medium heat. When oil is hot, add chickpea balls. Don’t overcrowd the pan. Deep fry falafels. Drain on an absorbent towel.
To bake: Preheat oven to 190C / 375 F. Arrange falafel balls on a baking tray lined with baking paper. Spray with a little cooking oil. Bake for 20-25 minutes.
To air fry: Place the balls in basket and air fry at 350F or 180C for 8-10 minutes. Flip and fry for another 5-6 minutes.
Serve with tahini yogurt sauce if you like. To make the sauce, grind together ¼ cup yogurt, 1 tablespoon lemon juice, a handful of coriander (cilantro) leaves and 2 tablespoons tahini. Season with salt and pepper.