Wash the potatoes thoroughly under cold running water and place them whole in a pot covered with cold water, adding a pinch of salt.

Boil the potatoes on medium-high heat, then reduce to a simmer and cook for 15–20 minutes until fork-tender.

While boiling, whisk together olive oil, lemon juice, sumac, salt, and pepper in a medium bowl to make the dressing.

Once cooked, drain the potatoes and allow them to cool slightly before cutting into bite-sized cubes.

In a large mixing bowl, combine the cubed potatoes with parsley, onion, cucumber, tomato, olives, and feta.

Pour the dressing over the mixture and toss gently without mashing the potatoes.

Taste and adjust seasoning if necessary, then let rest in the fridge for at least one hour before serving.

Serve at room temperature or chilled, garnished with parsley.