Mix the ricotta, lemon zest and parmesan in a bowl and season. Open each courgette flower and remove the stamen. Fill each flower with the ricotta mix.
For the tapenade, whizz the olives, red onion, garlic, capers, parsley and lemon juice in a food processor to a coarse paste. Gradually add the oil until you have a smooth consistency.
Pour the soda water into a bowl, add the flour and lightly mix until just combined. Fill a pan one third full of oil and heat. Test by dropping in a piece of bread - if it sizzles and floats to the top, the oil is hot enough. Dust the flowers with extra flour and coat in the batter. Lower into the oil in batches and fry for a couple of minutes until crisp and golden. Serve with ciabatta, the tapenade and a lemon cheek.