Soak the sliced onion in cold water for 10 minutes.In the meantime, prepare the batter: mix the dry ingredients (sifting the flour in will make the batter smoother).
Add about 100ml cold water slowly, mixing he batter continuously with a whisker, so everything is evenly distributed. If it's too stiff, add some more water. If it's too watery, add some more flour and teeny bit more salt.
Preheat your air fryer to 175C.
Fry them for 10 -15 minutes on 175C then turn the heat up to for the last 5 minutes or so to 200C so they get a bit crispy on the outside.
Prepare the raita: peel and chop the cucumber to small pieces, finely chop the fresh mint and mix with the yogurt and add the lemon juice and zest.