Grate the courgettes on the coarse side of a grater, then squeeze out the pulp to remove any excess liquid. Combine the courgette pulp in a bowl with the flour, mint and seasoning.
Pour the oil into a deep pan to 1cm depth and heat to 180°C, 350°F. Test either with a probe thermometer or drop a teaspoon of the mixture in: if it turns golden-brown within 30 seconds, the oil is hot enough.
Drop tablespoons of the batter into the oil in batches and fry on all sides until crisp and golden-brown. Remove with a slotted spoon and drain on kitchen paper. Serve with the lemons squeezed over.