In a bowl, whisk together all the shawrma marinade ingredients.
Add the chicken breast pieces to the marinade and coat well. Set aside.
Heat a non-stick skillet over medium-high heat. Add the chicken and cook for about 5 minutes on each side. Transfer to a cutting board and chop to slices.
Meanwhile, prepare the garlic yogurt sauce by mixing yogurt, garlic, lemon juice, mayonnaise, and salt in a small bowl until smooth.
To assemble the bowl, start with a base of cooked white rice.
Top the rice with the sliced shawarma chicken.
Add the cucumber, cherry tomatoes, crumbled feta cheese, and pickled onions.