Heat the olive oil in a large pan over medium heat. Sprinkle the chicken with salt and pepper on both sides and place in the pan. Cook for 5-6 minutes per side until the chicken is cooked through. Set aside and rest for 5 minutes, then shred.
In a food processor or blender, combine the chipotle peppers, adobo, cilantro, and lime juice. Blend until smooth.
Add the bell pepper, adobo mixture, and chicken to the sauté pan on low heat. Stir well to combine and cook for 3-4 minutes. Add the scallions to the pan. Spoon the mixture into lettuce wraps and serve.