Cut steak into small slices, melt butter in pan and add paprika and onion then slowly fry.

Add mushrooms and fry for 3 mins, transfer to warm plate.

Season beef then fry for 5-6 mins then transfer to warm plate.

Return onion mixture to pan and pour in sour cream then bring to boil, simmer for 1 min.

Return steak to pan and cook for further min. Stir in lemon juice and parsley then serve with matchstick chips.