Cut the chicken breast into 1-inch bite-sized pieces and pat them thoroughly dry with a paper towel.
In a medium bowl, toss the chicken with arrowroot powder, sea salt, and black pepper until every piece is 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 sesame oil in a large skillet or wok over medium-high heat until it begins to shimmer.
Add the chicken to the skillet in a single layer and cook for 5-6 minutes, turning occasionally, until the exterior is golden-brown and crispy.
Remove the chicken from the pan and set aside; immediately add the broccoli and bell peppers to the same pan with a splash of water to deglaze.
Sauté the vegetables for 3-4 minutes until tender-crisp, then stir in the pineapple chunks for 1 minute.
Return the chicken to the pan and pour the prepared sauce over the mixture, tossing constantly for 1-2 minutes until the sauce thickens into a glossy glaze.