In a small bowl, whisk together the olive oil, red wine vinegar, lemon juice, dried oregano, and minced garlic. This will be the dressing for your salad.
Layer the salad ingredients in mason jars, starting with the dressing at the bottom. Add the diced cucumber, halved cherry tomatoes, thinly sliced red onion, crumbled feta, and Kalamata olives.
Top with the mixed greens, packing them in to ensure everything stays fresh. Seal the jars tightly.
When you're ready to eat, shake the jar to mix the dressing and enjoy!
Notes
This salad can be stored in the refrigerator for up to 3 days, making it perfect for meal prep.