Pat the chicken breast dry and dice into small, even cubes, then season thoroughly with sea salt, black pepper, and garlic powder.
Heat the avocado oil in a large stainless steel or cast iron skillet over medium-high heat until shimmering.
Add the chicken to the hot skillet and sear for 5-6 minutes, stirring occasionally, until the edges are golden brown and the meat is cooked through.
Remove the chicken from the pan and set aside; in the same pan, add the frozen peas and carrots mix along with the white parts of the sliced green onions.
Sauté the vegetables for 3-4 minutes until tender, then push them to the outer edges of the skillet to create an open space in the center.
Crack the egg into the center of the pan and whisk quickly with a spatula until scrambled and just set.
Add the cooked brown rice and toasted sesame oil to the skillet, tossing with the vegetables and egg while pressing the rice down to allow it to crisp for 2 minutes.
Return the cooked chicken to the pan and drizzle with coconut aminos, stirring constantly for 1 minute to glaze every ingredient.
Remove from heat and garnish with the green onion tops and sesame seeds before serving warm.