It's an unorthodox batter recipe, as it originally comes from Greek peasants, not home chefs with aspirations to fling in eggs, beer, yeast, etc., all of which are expensive and unnecessary.
Once you have sliced as many courgettes as you want to serve, pour an amount of flour you judge to be enough to coat the number of fritters into a big mixing bowl. Take a fork and put the bowl under a slowly running tap of cold water. Begin beating to incorporate the water into the flour and beat out any lumps. As soon as the batter becomes the consistency of double cream, it's ready.
If your double cream is less thick than that found in Britain (its butter fat content in most of the rest of the world is much lower than that of British double cream) and it doesn't stick to the slices, just sprinkle a spoonful more flour and beat in until it does stick. If it's so thick it's difficult to move the slices around in it, just add more water.
Fry the fritters in small batches until golden on both sides, then set on paper towel to absorb the excess oil. Scatter a decent pinch of sea salt over the fritters before serving with aillou.