In slow cooker, combine onion, garlic, chicken, lemon pepper, oregano, and allspice.

Mix to coat chicken with seasoning.

Cover and cook on LOW for 4-6 hours.

Heat pita bread as directed on package.

Meanwhile, remove chicken from slow-cooker and place on cutting board.

Using two forks, shred chicken.

To serve, stir yogurt into onion mixture in slow cooker. Spoon chicken onto warm pita bread. With slotted spoon, transfer onion mixture onto chicken. Top with tomato, cucumber, and red pepper strips.