For the deep-fried courgette flowers, heat the vegetable oil in a deep-fat fryer, or fill a large, deep, heavy-based pan two-thirds full with vegetable oil. Heat the oil to 190C/375F (use a probe thermometer to check the temperature if you're not using a deep-fat fryer). (CAUTION: Hot oil can be dangerous. Don't leave unattended)
Mix the cornflour and salt in a bowl. Whisk in enough sparkling water to form a smooth batter (you may not need all the water).
Dip the courgette flowers into the batter and place in the deep-fat fryer, taking care not to overcrowd the fryer (you may need to do this in batches). Fry for two minutes. Once cooked, carefully remove from the oil using a slotted spoon and drain on a plate lined with kitchen paper. Season with salt and pepper.
For the onion bhaji, mix the onions, chickpea flour, ground coriander seeds and green chilli together with enough water to bind into a thick batter mixture. Add the salt, chilli powder and turmeric and mix thoroughly.
Gently drop a little of the bhaji mixture into the hot oil or deep-fat fryer to test it's hot enough.
When ready, place golf-ball sized amounts of the mixture into the oil. Fry until golden-brown.
Remove from the oil and drain on kitchen paper.
For the sweetcorn salsa, place all of the salsa ingredients into a large bowl and mix to combine. Season, to taste, with salt and freshly ground black pepper.
To serve, place the deep-fried courgette flowers and onion bhajis on a serving plate with the sweetcorn salsa alongside.