Dice the chicken breast into 1-inch cubes and season with the sea salt and black pepper.
In a small bowl, whisk together the coconut aminos, rice vinegar, honey, and arrowroot powder until smooth.
Heat the avocado oil in a large skillet over medium-high heat.
Add the chicken cubes to the skillet and cook until golden brown and fully cooked through, about 5 to 7 minutes.
Remove the chicken from the skillet and set it aside on a plate.
In the same skillet, add the diced red bell pepper, red onion, minced garlic, and grated ginger, sautéing until the vegetables are crisp-tender.
Stir in the pineapple chunks and cook for another 60 seconds until they are warmed through.
Return the cooked chicken to the skillet and pour the prepared sauce over the mixture.
Toss everything together for 1 to 2 minutes until the sauce thickens and creates a glossy coating over the ingredients.
Serve the sweet and sour chicken immediately over the warm cooked brown rice.