Stir together the ricotta, egg yolks, flour, lemon zest, salt and sultanas. Beat the egg whites until stiff peaks form. Fold through the ricotta mixture.

Heat the oil in a saucepan over medium heat. Drop tablespoons of the mixture into the oil and cook, a few at a time for 2-3 minutes until golden brown. Remove from the pan with a slotted spoon and drain on paper towels while you cook the rest. Serve immediately, drizzled with citrus sauce.

Put the sugar and 125ml of water in a small deep saucepan over high heat and boil without stirring. Brush the side of the pan with a wet pastry brush to prevent the sugar crystalizing. Once the caramel turns a rich golden colour, remove from the heat and add the lemon juice and zest. The caramel with splatter, so stand back. Stir gently until the sauce is smooth.