1. Preheat your air fryer to 360°F (180°C).
2. In a mixing bowl, combine chickpea flour, cumin seeds, crushed coriander seeds, turmeric powder, salt, and chili powder.
3. Gradually add water to the dry ingredients, whisking until you get a thick batter.
4. Add the sliced onions to the batter and mix well to coat them evenly.
5. Grease the air fryer basket with a little oil.
6. Place small portions of the onion mixture in the air fryer basket, making sure they don't overlap.
7. Air fry for 15-20 minutes, or until golden brown and crispy, shaking the basket halfway through.
8. Serve hot with your favorite chutney or dipping sauce.