Potato Salad with Homemade Mayonnaise

Wash the potatoes thoroughly and place them in a pot. Pour in enough water to reach about two finger-widths above the potatoes, then add 1 teaspoon of the salt.

Bring the water to a boil and cook the potatoes for another 25 to 30 minutes. Check whether they are tender by piercing them with a sharp, narrow knife.

Drain the cooked potatoes. As soon as they are cool enough to handle, peel them, cut them into thin slices, and transfer them to a salad bowl. Cover the bowl to keep the potatoes warm.

To make the mayonnaise, whisk the fresh egg, mustard, and 1 teaspoon of the oil together in a small heatproof bowl. Season with some of the salt and ground pepper, then pour in the hot vinegar.

Whisk the mixture over a water bath until the mayonnaise thickens. Remove it from the heat and, while whisking continuously, slowly pour in the remaining oil in a thin stream.

Peel and finely chop the onion. Wash, dry, and finely chop the parsley.

Pour the warm homemade mayonnaise over the potatoes. Sprinkle with the onion and parsley and gently toss everything together.

Serve the potato salad on plates and, if desired, garnish with a few parsley leaves.