Cook the Green Beans: In a large pot of boiling water, cook the green beans until they are bright green and tender-crisp, about 3 to 5 minutes.

Once cooked, drain the beans in a colander and run them under cold water to stop the cooking process. Set them aside.

Prepare the Dressing: In a small bowl, whisk together the olive oil, lemon juice, red wine vinegar, Dijon mustard, and dried oregano.

Season with salt and pepper to taste. Set aside.

Assemble the Salad: In a large bowl, combine the green beans, halved cherry tomatoes, crumbled feta cheese, and pitted Kalamata olives.

Pour the dressing over the salad and toss until everything is evenly coated.

Serve: Serve immediately or store in the refrigerator for up to 4 days.