Wash the potatoes and cut them into halves or quarters, depending on their size. Bring a large pot of water to a boil, add the potatoes, and cook for 10–12 minutes, or until fork-tender but still firm.
Drain the potatoes and rinse them with cold water to stop them from cooking.
Add the cooled potatoes to a large bowl. Add the herbs, feta, onion, and seasonings. Gently toss everything together.
Add the olive oil, lemon juice, and red wine vinegar to a jar. Seal the jar and shake until the dressing is well mixed.
Pour the dressing over the potatoes and gently toss to coat.