Mix the grated zucchini with salt in a bowl. Let stand for 15 minutes then rinse. Wrap zucchini in clean porous kitchen cloth, to squeeze out excess liquid.
Heat oil in a fry pan, add onion and garlic, cook gently until soft, about 4 minutes. Add the corn, cook for a further 4 minutes.
In a large bowl place polenta, flour, salt, baking powder and cheese. Mix well.
Add cooked vegetables, beaten egg and yogurt to the bowl, mix well.
Heat oil in a large non-stick fry pan over a medium heat. Measure out ⅓ cups of the mix into the pan. Cook until fritters are golden, 3 minutes on each side. Drain on paper towel.
poached eggs
To make poached eggs, fill a shallow pan with hot water and two tablespoons of white vinegar. Bring to the boil, and then reduce to a simmer.
Crack the egg into a little bowl first, and then when water is barely at a simmer, slide the eggs into the saucepan. Repeat for remaining eggs.
Turn off the heat and cover the pan. Set a timer for 6 minutes.
After 6 minutes remove eggs with a slotted spoon onto a paper towel to drain excess water.
To serve, place poached eggs onto warm zucchini fritters along with rocket leaves and tomato relish.