Combine the spices, garlic, and 2 tablespoons oil in a large bowl. The mixture will form a thick paste. Next, add the chicken strips and onions. Combine the chicken with the paste.
Heat 2 tablespoons of oil in a large heavy-duty pan or skillet. After the pan is very hot toss in the chicken and onion mixture. Sautee for 2-3 minutes or until he chicken is lightly charred and the onions are soft.
To Assemble: to make a shawarma sandwich, lay a pita flat on a plate with a sheet of foil under it. Top with chicken, veggies and shawarma sauce.