Place grated zucchini and 1/4 teaspoon of salt together in the centre of a clean Chux or cheesecloth. Place Chux in a sieve and sieve to stand over a mixing bowl for 10 minutes before squeezing, to remove excess water from the zucchini.
In a large mixing bowl, combine squeezed zucchini, spring onions, chilli, zest and mint, stirring until well combined.
Add flour, feta, parmesan, eggs, salt and pepper, stirring until combined.
Heat 1 tbsp of olive oil in a large non-stick frying pan, over a medium heat. Add 1/4 cup of zucchini mixture in batches of four and cook for 4 minutes on each side or until golden and cooked through. Add extra oil with batches, as required.
For the yogurt sauce, combine yogurt, lemon juice, salt and pepper together in a small bowl, stirring to combine.
Serve fritters with smoked salmon, sliced avocado, baby rocket, lemon wedges and yogurt sauce.