In a large bowl, mix together the ginger, garlic, chilli powder, ½ tsp of the turmeric, garam masala and lime zest and juice until well combined.
Add the chicken and season generously with salt and freshly ground black pepper. Stir to coat, then cover with cling film and leave to marinade in the fridge for 1 hour.
Meanwhile, make the homemade mint and coriander chutney (if wished): put the mint, coriander, garlic, lime juice, sugar, salt, shredded coconut and chilli in a food processor and blitz until smooth. Taste and adjust the flavours as necessary - adding more sugar (for sweetness), salt, lime juice (acidity) or chilli (for heat) depending on your personal preference. If you prefer a milder chutney, de-seed the chilli or omit altogether. Pour into a bowl, cover and chill until ready to serve.
For the batter: in a large bowl, lightly whisk together the gram flour, remaining ½ tsp turmeric and a pinch of salt. Whisk in the sparkling water until you have a smooth batter.
Fill a large deep-saucepan, casserole pan or deep-fat fryer ⅓ full of oil and heat until it reaches 180C. Line a plate or baking tray with kitchen paper.
Tip the marinated chicken pieces into the batter and stir to coat. Using tongs, remove the chicken pieces individually and carefully lower into the hot oil and fry for about 4 minutes - or until crispy and golden brown. Once you get the hang of it, you can fry in batches of 3 or 4 at once - don’t do too many or you will overcrowd the pan (the exact number you can do at once will depend on the size of the pan).
Carefully remove the prawns from the oil using a slotted spoon and place on the kitchen-paper lined plate or baking tray to absorb any excess oil. Repeat with the remaining chicken pieces.
Serve warm with the homemade mint and coriander chutney, yoghurt and fresh cucumber, garnished with herbs, with wedges of lime for squeezing over. Enjoy!