Combine your chicken and marinade in the ziploc bag (or large bowl) and let it sit for at least an hour.
Preheat the oven to 425 degrees F
Once the chicken has marinated for a while, put the chicken in a flat baking dish and cover it with sliced red onion. Lay the meat so it overlaps in the pan.
Bake chicken for half an hour.
Start cooking your rice in a pot on the stovetop while you wait for your chicken to bake. Add any spices you want to at this time.
Take your chicken out of the oven and let the meat rest for 5-10 minutes
While your meat is resting dice up the vegetables you would like to serve with your shawarma and prepare the white sauce to drizzle over the top.
Salt and pepper your food to taste.
Once you have everything cooked simply dish it all onto a plate and enjoy the fruits of your work!