1. Working with one piece of chicken at a time, place between sheets of plastic wrap and pound with a meat mallet or heavy skillet until flattened to an even 1/4" thickness.
2. Place pecans, breadcrumbs, orange zest, salt, and chipotle in a food processor and pulse until the pecans are finely ground. Transfer the mixture to a shallow dish.
3. Whisk egg white and water in a shallow dish until combined. Dip each chicken breast in the egg-white mixture, then dredge both sides in the pecan mixture.
4. Heat 1 1/2 teaspoons oil in a large skillet over medium heat. Add half the chicken and cook until it reaches a minimum internal temperature 165 degrees F (3-5 minutes per side). Transfer to a plate and cover to keep warm. Repeat with remaining chicken.