Preheat the oven to 200C/400F/Gas 6.
Place the vegetable oil into a deep, heavy-bottomed saucepan and heat until a small cube of bread sizzles and turns golden when dropped into it. (CAUTION: hot oil can be dangerous. Do not leave unattended.)
To make the turkey kiev, cover the turkey breast with cling film and bash with a meat mallet or rolling pin until it is 0.5cm/¼in thick.
Place the cream cheese and sage into the centre of the flattened turkey breast and season well with salt and freshly ground black pepper.
Fold the turkey in half over the filling and secure with cocktail sticks. Transfer to the fridge for five minutes.
Place the flour, beaten egg and breadcrumbs into three separate bowls. Season the flour with salt and freshly ground black pepper.
Remove the turkey from the fridge, remove the cocktail sticks and dip the turkey first into the flour, then the egg and finally the breadcrumbs.
Carefully place the turkey into the hot oil and deep fry for 3-4 minutes, or until golden-brown. Remove from the oil with a slotted spoon and drain on kitchen paper.
Place the turkey onto a baking sheet, transfer to the oven and bake for 10-12 minutes, or until completely cooked through.
For the rösti, place the grated potato into a clean tea towel and squeeze the tea towel over a bowl to remove the excess moisture.
Melt the butter in a small frying pan, add the grated potato and press into the pan to form a disc 1cm/½in thick. Season well with salt and freshly ground black pepper and fry for 2-3 minutes, or until the base begins to turn golden-brown. Turn over and cook on the other side for 2-3 minutes.
To serve, place the potato rösti onto a plate and top with the kiev, sliced in half on the diagonal, with the steamed broccoli alongside.