Pat the chicken breast dry with paper towels and cut into bite-sized pieces.
In a medium bowl, toss the chicken with arrowroot powder, sea salt, and black pepper until evenly coated.
In a small jar or bowl, whisk together the coconut aminos, rice vinegar, tomato paste, honey, minced ginger, and minced garlic to create the sauce.
Heat the avocado oil in a large non-stick skillet or wok over medium-high heat.
Add the chicken to the pan in a single layer and sear for 3-4 minutes per side until golden brown and crispy, then remove and set aside.
Add the sliced bell peppers and pineapple chunks to the same pan, sautéing for 3 minutes until the peppers are tender-crisp.
Return the chicken to the pan and pour the sauce over the mixture.
Stir constantly for 1-2 minutes until the sauce thickens into a glossy glaze that coats the chicken and vegetables.
Remove from heat, drizzle with sesame oil, and serve immediately.