Divide the chicken breasts into two natural fillets, place between two sheets of  clear film and flatten each to a thickness of 5mm with a rolling pin.

Cut into 2.5cm/1 in strips diagonally across the fillets.

Heat 30ml/2 tbsp oil in a large frying pan and cook the sliced onion slowly until soft but not colored.

Add the mushrooms and cook until golden brown. Remove and keep warm.

Increase the heat, add the remaining oil and fry the chicken very quickly, in small batches, for 3-4 minutes until lightly colored. Remove and keep warm while frying the rest of the chicken.

Return all the chicken, onion and mushrooms to the pan and season with salt and pepper.

Stir in the soured cream and bring to the boil. Sprinkle with fresh parsley and serve immediately.