1 cup plain nonfat yogurt
4 tablespoons chopped green onions
2 chipotle peppers
4 tablespoons peanut butter
1/4 teaspoon salt

1 pound skinless, boneless chicken breast halves - cut into 1/2 inch strips
1/2 teaspoon salt
1/2 teaspoon pepper
1/2 teaspoon chili powder
1/2 teaspoon garlic powder
1/2 teaspoon dried oregano
1/2 teaspoon ground cumin
3 tablespoons vegetable oil, divided
1 medium onion, sliced
1 red bell pepper, julienned

4 (6-inch) pitas
1 cup shredded lettuce
1 cup shredded white Cheddar cheese