Bring a large pot of water to boil. Peel corn husks off and cook corn for 5 minutes. drain and allow cobs to cool.
Grate courgette and place into a medium bowl. Cut half of the feta into small cubes and add to courgettes. Add cornflour, baking soda, salt and pepper into the bowl.
Once corn is cool, cut kernels from the cob, place half in the courgette bowl and the other half into a food processor with half the feta and eggs and blitz till it's a rough paste. Add corn paste to the courgette bowl to combine all ingredients.
Heat a large fry pan with olive oil. Use a 1/3 cup measurer to scoop the fritter mix into the pan to cook similar sized fritters. Cook until golden brown on one side before flipping over, this takes about 2-3 minutes. Once browned on both sides, place on a lined oven tray on your oven until ready to assemble burgers.
Slice Baps in half and toast cut side down in a buttery pan (or in your toaster if preferred).
Slice red onion and cucumber into generous sized rings (this will make for a great crunchy texture)
To assemble, we put a handful of spinach down, then two fritters, cucumber, onion the mayo and you are ready to eat.