In a large pot, bring salted water to a rolling boil over high heat. Once boiling, add the fresh green beans and cook for 2 minutes. Drain the beans in a colander and pat them dry.

In a large mixing bowl, combine the cooked green beans with the halved grape tomatoes, sliced Vidalia onion, and crumbled feta cheese. Stir gently to mix without breaking the feta.

In a small bowl or jar, whisk together the lemon juice, olive oil, Dijon mustard, minced garlic, salt, and pepper until emulsified.

Drizzle the dressing over the salad ingredients and gently toss until everything is evenly coated in the dressing.

Allow the salad to marinate at room temperature for 15 minutes to let the flavors meld.

Give the salad a final gentle toss before serving. Serve chilled or at room temperature.