Warm up a medium-sized skillet on medium-high heat on the stove, add in the oil, and begin by warming up and simmering the chicken for about 2 minutes.
Add in the onion, celery, and carrots and continue to simmer for about 5 minutes or until the onions are translucent.
Keeping the heat on medium-high heat, add in the cooked and cold rice.
Stir in about 2 TBSP of soy sauce or enough to turn the rice to a brown color. Continue simmering and cooking this for about 10 minutes or until heated through.
Stir in the beaten egg, and let this cook for 1-2 minutes until it's fully cooked and incorporated.
If you want it darker in color add in the remaining soy sauce or additional to taste preference. Serve with green onion to garnish.
This dish makes about 4 servings depending on size.
Notes
This is a wonderful way to use up stored rice that has been previously cooked. This dish is made with cooked and cold rice.