In a large mixing bowl, combine tahini, za'atar, red wine vinegar, fresh lemon juice, and minced garlic. Whisk until smooth and creamy.

Add the boneless, skinless chicken thighs to the bowl with the marinade, ensuring each piece is coated. Marinate in the refrigerator for at least 1 hour.

Preheat your oven to 425°F (220°C). Line a baking sheet with parchment paper.

Remove the chicken from the marinade and place it on the baking sheet. Roast for about 35 minutes, or until golden brown and cooked through.

While the chicken is baking, take the reserved marinade and add a little water to achieve a creamy consistency for the tahini sauce.

Once the chicken is done, let it rest for a few minutes. Serve topped with the tahini sauce and garnish with parsley.

Pair with refreshing salad or flatbreads for a complete meal.