1. Preheat the oven to 190°C.

2. Season the chicken breasts with oregano, garlic powder, salt, and pepper. Heat a skillet over medium-high heat and add the olive oil. Once hot, add the chicken breasts and cook for 3-4 minutes per side until browned.

3. Transfer the chicken breasts to a baking dish and bake in the oven for 15-20 minutes or until cooked through.

4. In a small bowl, whisk together the red wine vinegar, lemon juice, Dijon mustard, and a pinch of salt and pepper.

5. In a large bowl, combine the romaine lettuce, cucumber, cherry tomatoes, red onion, feta cheese, and kalamata olives.

6. Once the chicken is done cooking, let it rest for a few minutes before slicing it into strips.

7. Add the sliced chicken to the salad bowl and drizzle the dressing over it. Toss everything together until well combined.

8. Serve immediately and enjoy your delicious keto Greek salad with chicken!