Grilled Chicken Pitas with Sesame Drizzle

tahini (roasted sesame seed paste)

water

fresh lemon juice, divided

extra-virgin olive oil, divided

kosher salt, divided

small garlic clove, minced

skinless, boneless chicken breast halves

freshly ground black pepper

Cooking spray

whole-wheat pitas, cut in half

shredded romaine lettuce

bottled roasted red bell peppers, drained and thinly sliced