Pat the chicken breast dry and dice into small, even bite-sized pieces, then season with sea salt and black pepper.
Whisk the egg in a small bowl and set aside; mince the garlic, grate the fresh ginger, and thinly slice the green onions.
Heat the avocado oil in a large wok or non-stick skillet over medium-high heat until shimmering.
Add the chicken to the pan and cook for 4-5 minutes until golden brown and cooked through, then remove the chicken and set aside.
In the same pan, add the frozen peas and carrots, garlic, and ginger, sautéing for 2 minutes until the vegetables are tender and aromatic.
Add the chilled cooked rice to the pan, breaking up any clumps with a spatula, and stir-fry with the vegetables for 2-3 minutes.
Push the rice and vegetable mixture to one side of the pan and pour the whisked egg into the empty space, scrambling until just set.
Return the chicken to the pan and drizzle with tamari and toasted sesame oil, tossing everything together to combine and heat through.
Remove from heat and garnish with the sliced green onions before serving warm.