Pat the chicken breast dry with paper towels and toss in a bowl with arrowroot powder, sea salt, and black pepper until evenly coated.
In a small jar or bowl, whisk together the coconut aminos, rice vinegar, honey, minced ginger, and minced garlic to create the stir-fry sauce.
Heat the avocado oil in a large non-stick skillet or wok over medium-high heat.
Add the chicken to the skillet in a single layer and sear for 3-4 minutes per side until golden brown and cooked through, then remove and set aside.
In the same skillet, add the sliced bell peppers and pineapple chunks, sautéing for 3 minutes until the peppers are tender-crisp and the pineapple is slightly caramelized.
Return the chicken to the skillet and pour the sauce over the mixture.
Toss everything together for 1 minute until the sauce thickens into a glossy glaze that coats the chicken and vegetables.
Garnish with sliced green onions and serve immediately.