In a large bowl, whisk together Greek yogurt, lemon juice, olive oil, red wine vinegar, garlic, oregano, paprika, cumin, coriander, cayenne, salt, and pepper.
Add the chicken tenders and coat well with the marinade. Cover and refrigerate for at least 30 minutes or overnight for the best flavor.
Prepare your homemade Greek dressing and set it aside.
In a large salad bowl, combine romaine lettuce, tomatoes, bell pepper, cucumber, shallots, and Kalamata olives.
Toss the vegetables with about 4 tablespoons of the dressing.
Sprinkle feta cheese over the salad.
Heat one tablespoon olive oil in a skillet over medium-high heat.
Remove excess marinade from the chicken and cook for about 5 minutes per side until golden brown and the internal temperature reaches 165°F (74°C).
Assemble the Greek Grilled Chicken Salad by placing cooked chicken over the prepared salad.
Drizzle with the remaining Greek dressing and serve immediately.