Cut cold boiled potatoes into tiny dice of uniform size.
Put two great spoonfuls of butter into the frying pan and fry two sliced onions in this for three minutes.
With a skimmer remove the onions and turn the potatoes into the hissing butter.
Toss and turn with a fork, that the dice may not become brown.
When hot, add a teaspoon of finely chopped parsley and cook a minute longer.
Remove the potatoes from the pan with a perforated spoon, that the fat may drip from them.