Cut the chicken breast into bite-sized 1-inch cubes and place them in a bowl.
Toss the chicken with arrowroot powder, sea salt, and black pepper until evenly coated.
In a small jar or bowl, whisk together the tomato paste, coconut aminos, rice vinegar, 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 skillet in a single layer and cook for 5-6 minutes, turning occasionally, until golden brown and crispy on all sides.
Remove the chicken from the pan and set aside on a plate.
In the same skillet, add the sliced bell peppers and pineapple chunks, sautéing for 3-4 minutes until the peppers are tender-crisp.
Pour the sauce mixture into the skillet and bring to a simmer for 1 minute until it begins to thicken.
Return the crispy chicken to the pan and toss well to coat every piece in the glossy sauce.
Drizzle with toasted sesame oil before serving immediately.