Chicken Shawarma with Creamy Garlic Sauce

For the Chicken:
2 lbs boneless, skinless chicken thighs or breasts
1 tablespoon ground cumin
1 teaspoon ground coriander
1 teaspoon paprika
1/2 teaspoon turmeric
1/2 teaspoon ground cinnamon
1/2 teaspoon ground ginger
1/4 teaspoon cayenne pepper (adjust to taste)
1 tablespoon lemon juice
2 tablespoons olive oil
Salt and pepper, to taste
For the Creamy Garlic Sauce:
1/2 cup plain Greek yogurt
1/4 cup mayonnaise
2 cloves garlic, minced or grated
1 tablespoon lemon juice
Salt, to taste
Instructions: