4 large red onion rings, about 5mm/ΒΌin thick
lime pickle
4 tbsp mayonnaise
1Β½ tbsp chaat masala
oil, for greasing the tray
pinch salt
200g/7oz Bombay mix, plus extra for serving
4 spicy cheese slices
1 medium free-range egg, beaten
4 brioche burger buns or mini naans