Chicken Shawarma

Name: Chicken Shawarma
Ingredients: 1 cup Cucumber ; shredded; 1/4 cup low fat plain yogurt; 3 tablespoon Sesame tahini; 2 tablespoons Lemon Juice; 1/2 teaspoon salt ; divided; 1 tablespoon Garlic powder; 1 teaspoon Curry powder; 1/2 teaspoon Freshly ground pepper; 1 pound Chicken breasts boneless and skinless ; trimmed; 1 tablespoon Canola Oil; 4 Whole wheat pita breads ; 6 inch; 1 medium tomato; 2 cups Romaine ; thinly sliced