If you're starting with pre-cooked chicken, simply set it aside to add later. If you're starting with a raw chicken breast, heat your skillet over medium-high heat and add a small amount of oil.
Cut up the chicken breast into 1-inch sized pieces and season the chicken with some salt and pepper. Cook in the hot skillet until the chicken pieces are golden brown and cooked through to an internal temperature of 165 degrees Fahrenheit (74 degrees Celsius). Remove the chicken from the pan and set aside.
Add the sesame oil and coconut oil (or vegetable oil) to the hot skillet.
Add the sliced leek, onion, carrots, celery and garlic and cook over medium heat until the vegetables are soft.
Add the soy sauce and pepper and stir well.
Add the eggs into the middle of the pan (push the veggies to the sides of the pan) and scramble them, cooking until they're just cooked through.
Add the cooked rice and the cooked chicken and stir everything together well over the heat until the rice absorbs the soy sauce and browns slightly.
Add a little more soy sauce (if desired, to taste), top with some chopped green onions and serve!