In a small bowl, whisk together the cumin, coriander, turmeric, garlic powder, sea salt, and black pepper to create the shawarma spice blend.
Rub the spice blend evenly over both sides of the chicken breast until well coated.
Heat the olive oil in a skillet over medium-high heat and sear the chicken for 6 to 7 minutes per side until golden brown and the internal temperature reaches 165 degrees.
While the chicken is cooking, combine the chopped cucumber, halved cherry tomatoes, diced red onion, and fresh parsley in a small bowl to create a quick salad.
In a separate small jar, whisk the tahini with the lemon juice and a tablespoon of warm water until the sauce is smooth and pourable.
Slice the cooked chicken into thin strips and arrange them over the warm, cooked brown rice in a serving bowl.
Top the bowl with the fresh vegetable salad and finish by drizzling the zesty tahini sauce over the top before serving.