Cut the chicken breast into bite-sized 1-inch cubes and place them in a bowl.
Toss the chicken with arrowroot starch, sea salt, and black pepper until evenly coated.
In a small jar, whisk together the coconut aminos, rice vinegar, tomato paste, and honey to create the sweet and sour sauce.
Heat avocado oil in a large 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 cooked through.
Remove the chicken from the pan and set aside.
In the same pan, add the sliced bell peppers and snap peas, stir-frying for 3 minutes until tender-crisp.
Add the pineapple chunks and the prepared sauce to the pan, stirring constantly as the sauce begins to bubble and thicken.
Return the chicken to the pan and toss everything together for 1 minute to ensure the chicken is well-coated in the glaze.
Garnish with sliced green onions and sesame seeds before serving.