01 - Bring a large pot of salted water to a rolling boil. Add trimmed green beans and cook for 3–4 minutes until just tender and bright green.
02 - Drain the beans and immediately transfer to a bowl of ice water to stop the cooking process. Drain thoroughly and pat dry with clean towels or paper towels.
03 - In a large mixing bowl, combine the blanched green beans, halved cherry tomatoes, and thinly sliced red onion.
04 - In a small bowl, whisk together extra-virgin olive oil, lemon juice, Dijon mustard, minced garlic, salt, and pepper until fully emulsified and smooth.
05 - Pour the dressing over the vegetable mixture and toss gently to coat all ingredients evenly.
06 - Add crumbled feta cheese and chopped fresh parsley. Toss lightly once more and serve immediately, or refrigerate for up to 2 hours to allow flavors to meld.