Arrange the onion skins to line the base of a large, deep stainless steel pan. Cradle the eggs on top of the onion skins in a single layer and pour over enough cold water to cover the eggs by 7.5cm (3in). Add the oil, coffee (if using), vinegar and salt and pepper. Cover and bring to a slow boil. Reduce the heat and simmer for at least six hours making sure they are completely covered and add more water when necessary.

Scoop out the eggs with a slotted spoon and run them under cold water until they are just cool enough to handle. Roll the eggs to crack the shells and then slip off the shells.

Cut the eggs in half and sprinkle with salt and pepper or cumin. Serve warm or at room temperature.

Stella’s Hints:

* The hard-boiled eggs can be refrigerated in their shells with the cooking liquid for up to a day. Before serving return to room temperature first and then bring the cooking liquid to a slow boil. Reduce the heat and simmer for 15 minutes.