To get started, shred your rotisserie chicken, discarding the skin and bones. Using cold, day-old rice ensures your dish won’t turn mushy. If you don’t have any rice already cooked, freshly made rice will work but be sure to chill it before use.
Heat a large skillet or wok over medium-high heat. Add a splash of oil and toss in the onion, celery, carrots, and red bell pepper. Stir them around until they begin to soften, which should take about five minutes. Add the garlic and cook for another 30 seconds to release its aroma.
Next, stir in the shredded chicken, frozen peas, and cold rice. Continue stir-frying for a couple of minutes to combine the ingredients and warm them through evenly. Break up any clumps of rice with your spatula.
While the rice is cooking, whisk together soy sauce, oyster sauce, sesame oil, and lemon juice in a small bowl. Pour this mixture over the chicken and rice in the skillet, stirring to coat every bite. Adjust seasoning with salt and pepper to taste.
Transfer the fried rice to a serving dish and sprinkle with chopped spring onions for a burst of freshness and color. Serve hot and enjoy the medley of flavors in every forkful.