Dice the chicken breast into small, uniform cubes and season with sea salt and black pepper.
Heat the avocado oil in a large skillet or wok over medium-high heat.
Add the chicken to the pan and sauté until golden brown and cooked through, about 5-6 minutes, then remove from the pan and set aside.
In the same pan, whisk the egg and scramble quickly until set, then remove and set aside with the chicken.
Add the toasted sesame oil to the pan, then stir in the minced garlic, grated ginger, and the white parts of the sliced green onions.
Toss in the frozen peas and carrots, sautéing for 2-3 minutes until tender.
Add the chilled cooked brown rice to the pan, breaking up any clumps, and cook for 3 minutes until the rice begins to crisp slightly.
Return the chicken and eggs to the pan, pour the tamari over the mixture, and toss everything together until well combined and heated through.
Garnish with the green tops of the sliced onions and serve immediately.