If using fresh peas, blanch them: bring a medium saucepan of salted water to a boil. Add peas and cook for 1-2 minutes until bright green and tender. Drain immediately and transfer to a bowl of ice water to stop cooking. Drain well and pat dry.

If using frozen peas, simply thaw them by running under cool water in a colander for 30 seconds, then drain thoroughly.

In a small bowl or jar, combine olive oil, lemon juice, lemon zest, Dijon mustard, salt, and pepper. Whisk or shake until emulsified.

In a large mixing bowl, combine the peas, crumbled feta, chopped mint, and sliced radishes (if using).

Pour the dressing over the salad and toss gently to combine. Taste and adjust salt or lemon if needed.

Serve immediately, or refrigerate for up to 2 hours before serving (toss again just before serving).