Bring a large pot of water to a boil. Add a pinch of salt, potatoes, and chopped onion. Cook until potatoes can be pierced with a fork— tender but firm. Approximately 15 minutes. Drain potatoes and let cool.

Pour Greek dressing onto potatoes, stir to coat, allowing the dressing to absorb as evenly as possible. This step can also be done when potatoes are still warm.

Once potatoes have cooled completely, add in mayonnaise, mashing potatoes as you stir until desired potato salad consistency is achieved.

Toss in feta cheese and kalamata olives, combine until well distributed. Add pepper if desired.

Refrigerate until ready to serve.