1. Clean the potatoes well under running water and put them in the pan.
  2. Add sufficient water to a saucepan and bring to the boil. Add the potatoes to the boiling water and cover.
  3. Boil the potatoes for 10-15 minutes until cooked but still firm. Turn off the heat under the potatoes and keep warm.
  4. Meanwhile, boil the eggs for 10 minutes and then submerge in cold water. Peel and halve the eggs.
  5. Heat the butter in a frying pan and fry the bacon until crispy.
  6. Remove the bacon from the frying pan and drain on some kitchen paper, then chop it into small pieces.
  7. Remove the leftover fat from the frying pan and add the gherkins, parsley, mayonnaise, sour cream and lemon juice to the pan.
  8. Heat the mixture on low heat and stir well.
  9. Put the sauce mixture in a bowl and stir in the potatoes, eggs and bacon.
  10. Season with salt and pepper to taste.