Chicken liver stroganoff

1 lb chicken livers
    1/2 lb Cap mushrooms
      2    Onions
  1 1/2 oz Unsalted or clarified butter
    1/2 pt Soured cream
      3 tb Fairly acid yoghurt
 
  Thoroughly heat a large saute or frying pan.  Add a scant 1/2 oz of the
  butter and tilt so that the fat runs sizzling all over the pan base. Add
  the mushrooms (whole if small or sliced thickly if large) and saute over
  high heat for 5 minutes.  Remove and keep hot.
  
  Add the rest of the butter to the pan, then the onions which should be
  thinly sliced and pushed into rings. Cook very gently indeed for 15-20
  minutes until beautifully softened. Meanwhile stir the yoghurt into the
  soured cream and season very generously with salt and pepper; trim the
  chicken livers and pat them dry with kitchen paper.
  
  Lift the onions out of the pan with a slotted spoon, so all the buttery
  juices drip back into the pan, and keep them hot. Increase the heat under
  the pan and saute the chicken livers for about 3 minutes so they become
  crusted with brown on the outside, but remain deliciously pink and tender
  within.
  
  Return the mushrooms and onions to the pan and immediately pour on the
  seasoned soured cream.  Let the sauce bubble up and cook for a few minutes
  until it is very hot, slightly reduced and thickened. Stir gently every now
  and again to encourage the sauce to cling creamily to the meat and
  vegetables.  Check seasoning and serve without delay. Green beans and
  triangles of fried bread go well with this dish, and I like to accompany it
  with plenty of crusty hot French bread to mop up every luscious drop of
  sauce.  More substantially, you could substitute rice or thin ribbons of
  pasta for the bread.
  
  Source: Philippa Davenport in "Country Living" (British), March 1988.