Begin by bringing a large pot of salted water to a rolling boil. Carefully add the peas and cook for exactly 5 minutes until tender-crisp and bright green. Drain and set aside.

In a small saucepan, heat olive oil over medium heat. Add minced onion and sauté for about 5 minutes until translucent.

Remove from heat, stir in white wine vinegar and let cool slightly.

Pour the warm dressing over the peas, folding gently to combine. Add radishes, mint, and chives.

Transfer to a serving dish, crumble feta on top, and season with additional salt and pepper to taste.