In a medium bowl, whisk together yogurt, sour cream and lime juice. Add cilantro, season with salt and pepper and set aside.
In a large skillet over medium heat, heat oil. Add chicken and season with salt, pepper, cumin and chili powder. Cook until golden and no longer pink, 8 minutes per side. Transfer to a plate to let rest, then slice into cubes and let cool completely.
In a large bowl, combine cooked chicken with avocado, beans, corn and red bell pepper. Toss with yogurt dressing until completely coated. Serve on bread, in lettuce leaves, or by itself.