In a small bowl, whisk together the cumin, coriander, turmeric, garlic powder, paprika, salt, and pepper to create the shawarma spice blend.
Slice the chicken breast into thin strips and toss thoroughly with the spice blend until evenly coated.
Heat the olive oil in a non-stick skillet over medium-high heat and add the chicken strips.
Sear the chicken for 6-8 minutes, turning occasionally, until golden brown on the outside and fully cooked through.
While the chicken is cooking, prepare the sauce by whisking the Greek yogurt and lemon juice together in a small ramekin until smooth.
Place the warm cooked basmati rice into the bottom of a serving bowl.
Top the rice with the spiced chicken, diced cucumber, halved cherry tomatoes, and finely minced red onion.
Drizzle the lemon-yogurt sauce over the bowl and garnish with freshly chopped parsley before serving.