Dice the chicken breast into small, even cubes and season with sea salt and black pepper.
Heat avocado oil in a large skillet or wok over medium-high heat until shimmering.
Add the chicken to the pan and cook until golden brown and cooked through, then remove and set aside.
In the same pan, whisk the egg and scramble quickly until just set, then remove and set aside with the chicken.
Add the toasted sesame oil to the pan, then stir in the diced carrots, frozen peas, minced garlic, and grated ginger, sautéing until fragrant and tender.
Increase the heat to high and add the chilled cooked brown rice, pressing it down to maximize contact with the pan for a crispy texture.
Return the chicken and egg to the pan, drizzle with tamari, and toss everything together until well combined and heated through.
Garnish with sliced green onions and sesame seeds before serving.