Stir together the ingredients for the za’atar spice blend in a small bowl.
Place the chicken in a zip lock bag or sealable container and drizzle with olive oil. Sprinkle with 2 tablespoons (or more) of the za’atar spice blend and sea salt. Seal the bag and shake/rotate the bag until the chicken is well-coated in spices and oil. Allow chicken to marinate at least 15 minutes, up to 12 hours
Preheat the oven to 450 degrees F. Place chicken in a casserole dish in a single layer, allowing space between each breast for even cooking. Bake chicken 20 minutes, or until the internal temperature reaches 160 degrees F. Transfer chicken to a cutting board and allow it to rest 5 to 10 minutes before slicing
Form bowls by dividing rice, chicken, and cucumber salad among 3 to 4 bowls. Drizzle with kefir raita and serve.
Prepare the Raita
Stir together the ingredients for the raita in a bowl until combined. Taste for flavor and add sea salt to taste. Refrigerate until ready to use.
Prepare the Cucumber Salad:
Combine the ingredients for the salad in a mixing bowl and toss together to combine. Set aside until ready to use.