Cut the onions in half and then finely slice them. Mix the salt into them and set aside for an hour or up to four hours.
After an hour the onions will be limp and moist. Squeeze the onions to release the water into the bowl. Add the remaining ingredients to the onions, being careful not to add to much gram flour. You should easily be able to pick up a ball of the onion mixture.
Divide the mixture in to small bhajis.
Heat the Air Fryer (Vortex or Dup Crisp) to 176°C and programme the time for 15 minutes. Spray the basket with oil spray generously.
Place the bhajis in the basket. You will need to cook these in batches.
After 15 minutes, your first batch will be cooked to perfection, then continue with the remaining bhajis.