In a small bowl, combine oregano, basil, thyme, paprika, garlic powder, 1 teaspoon salt and 1/2 teaspoon pepper. Season chicken with oregano mixture.
Preheat grill to medium heat.
Add chicken to grill, and cook, turning occasionally, until chicken is completely cooked through, reaching an internal temperature of 165 degrees F, about 10 minutes.
To assemble the salad, place romaine lettuce in a large bowl; top with chicken, cucumber, tomatoes, avocado, onion, olives and feta. Pour the tzatziki dressing on top of the salad and gently toss to combine.
Serve immediately.
For the tzatziki dressing
In a medium bowl, whisk together Greek yogurt, buttermilk, dill, lemon juice, lemon zest and garlic; season with salt and pepper, to taste. Set aside in the refrigerator up to 5 days in advance.
Notes
An outdoor grill is not necessary. Too cold to grill outside? A cast iron grill pan can be used to get those favorited grill marks and charred flavor.
Prep ahead of time. Save time by making the tzatziki dressing up to 5 days in advance, and prepping and dicing the vegetables 1-2 days prior and storing them in airtight containers in the fridge.
Cut in uniform size. Cut all of the salad ingredients in similar size pieces for a consistent bite.
Use extra virgin olive oil. High quality extra virgin olive oil is ideal for salad dressings.
Add some crunch. Add some pine nuts, sunflower seeds, chopped pecans or slivered almonds for an added crunch.
Use an instant-read thermometer for the most accurate results. The internal temperature of the chicken should reach 165°F.
Let your meat rest. Let your chicken rest for at least 5 minutes prior to slicing and serving, allowing the juices to redistribute – this will allow for maximum flavor and juiciness.
Toss the dressing just before serving. This will avoid a soggy salad and allow for maximum, crisp freshness, keeping the chicken, vegetables and dressing in separate airtight containers if meal prepping ahead of time.