Chicken Shawarma

Name: Chicken Shawarma
Ingredients: 1 Tablespoon Smoked Paprika; 1 Tablespoon Ground Cumin; 1 Tablespoon Ground Cardamom; 1 Tablespoon Chili Powder; 1 Tablespoon Ground Coriander; 3 cloves Garlic, Minced; 1 whole Lemon, Juiced, Divided; 2 pinches Coarse Salt And Freshly Ground Pepper; 5 Tablespoons Extra Virgin Olive Oil, Divided; 2 whole Boneless, Skinless Chicken Breasts; 1 whole White Onion, Sliced; 1 whole Green Bell Pepper, Sliced; ¼ cups Tahini; ½ cups Plain Greek Yogurt; ½ cups Cherry Tomatoes, Halved; 4 whole Pitas; ½ cups Shredded Romaine Lettuce