Preheat the deep fat fryer to gas 4, 180°C, fan 160°C . Alternatively, you can fill a large saucepan halfway with sunflower oil. Use a cooking thermometer to heat to 180°C. In a large mixing bowl, whisk together the lemonade and flour to make the batter. Set aside. This is a perfect job for the kids while you prepare the fish. Cut the cod fillets into 8 individual goujons. Dip each goujon in lemonade batter until completely covered. Carefully lower the fish into the deep-fat fryer or saucepan and cook for 4 minutes, or until golden brown and crispy. If the oil is hot enough and you don't keep the fish in there for too long, the food won't end up greasy. Remove the goujons from the fryer using a slotted spoon and set aside to drain on kitchen paper. Season to taste with salt and pepper. Serve with the lime segments and some dollops of tartare sauce.
