Add romaine lettuce, cucumber, tomatoes, red onion, olives, and feta cheese to a large bowl.
In a small bowl, whisk together olive oil, red wine vinegar, lemon juice, Dijon mustard, garlic, oregano, salt, and pepper.
Drizzle vinaigrette over the salad.
Toss gently until evenly coated.
Serve immediately.
Notes
• Dress the salad immediately before serving.• Fresh lemon juice provides the best flavor.• Store dressing separately when meal prepping.• Add grilled chicken for extra protein.• Feta cheese can be crumbled or served in larger chunks.