In a small bowl, combine the ground cumin, coriander, turmeric, garlic powder, sea salt, and black pepper to create the shawarma spice blend.
Slice the chicken breast into thin, bite-sized strips and toss them in the spice blend until every piece is thoroughly coated.
Heat the olive oil in a large skillet over medium-high heat and add the chicken strips, cooking for 6-8 minutes until they are browned and cooked through.
Prepare the dressing by whisking the tahini and lemon juice together in a small jar, adding a teaspoon of warm water at a time until it reaches a smooth, pourable consistency.
Dice the cucumber, halve the cherry tomatoes, and finely mince the red onion to prepare the fresh vegetable topping.
Assemble the bowl by placing the warm cooked rice at the bottom, layering the spiced chicken on top, and adding the fresh vegetables.
Finish the dish by drizzling the creamy tahini sauce over the top and serve immediately while the chicken is hot and fragrant.