1. In a large salad bowl, combine lettuce, cherry tomatoes, onion and avocado.
2. Marinate chicken breast with garlic,olive oil, mixed herbs,chilli flakes for 2-3 hrs. Grill it in a pan and keep aside.
3. In a small measuring cup, whisk together oil, vinegar, salt, pepper and oregano. Pour over salad and toss gently to coat.
4. Slice or chop grilled chicken breasts.
5. Place salad on serving plates. Arrange half of sliced grilled chicken breast on top of the salad, on each serving.
6. Serve immediately