Finely slice the onions, then throw them in a large bowl with the salt. Set them aside for at least 30 minutes. This will draw the water out of the onions.
2 large onions, 0.5 teaspoon salt
After 30 minutes, using your hands, start to squeeze as much water out of the onions as you can, into the bowl. No need to do this into a different bowl, as the 'onion water' is needed.
Next, preheat the air fryer to 180°c.
Place all the dry ingredients plus the oil into the bowl with the sliced onions. That includes the garlic, onion, ginger cumin seeds, mustard seeds, fennel seeds, fenugreek seeds, nigella seeds, gram flour, turmeric powder, fresh coriander and gram flour.
2 teaspoon garlic, 1 teaspoon ginger, 1 green chilli, 0.25 teaspoon cumin seeds, 0.25 teaspoon black mustard seeds, 0.25 teaspoon fenugreek seeds, 0.25 teaspoon fennel seeds, 0.25 teaspoon nigella seeds, 0.25 teaspoon turmeric powder, 1.5 tablespoon fresh coriander, 1 tablespoon oil, 1 cup chickpea flour
Combine it all together until a thick batter forms. It should be sticky but not runny, and you should be able to form a ball with the mixture without it falling apart or getting stuck to your hands.
Shape them into evenly sized balls, then pop them into the air fryer basket.
Optionally, spray with oil spray generously, as this will help them to brown.
Air fry for 15 minutes at 180°c.
Serve hot as a snack, starter or side dish.