Dice the chicken breast into small, bite-sized pieces and season with garlic powder, ground ginger, sea salt, and black pepper.
Heat the avocado oil in a large cast-iron skillet or wok over medium-high heat until shimmering.
Add the seasoned chicken to the skillet and sauté for 5-6 minutes until golden brown and cooked through, then remove the chicken and set aside.
In the same skillet, add the diced carrots and sauté for 3 minutes until they begin to soften, then stir in the frozen peas.
Push the vegetables to the outer edges of the skillet and crack the egg into the center, scrambling it quickly until just set.
Add the chilled brown rice and the cooked chicken back into the skillet, using a spatula to break up any rice clumps.
Drizzle the tamari and toasted sesame oil over the mixture and toss everything together for 2-3 minutes until the rice is heated through and slightly crispy.
Garnish with thinly sliced green onions and serve immediately while hot.