Whisk together the coconut aminos, rice vinegar, tomato paste, honey, ginger, and garlic in a small bowl to create the sweet and sour sauce.
Heat the avocado oil in a large skillet or wok over medium-high heat until shimmering.
Season the chicken breast with salt and pepper, then add to the skillet and sauté until golden brown and cooked through.
Remove the chicken from the skillet and set aside; add the bell peppers, snap peas, and pineapple to the same pan.
Sauté the vegetables for 3-4 minutes until they are tender-crisp, then return the chicken to the skillet.
Pour the prepared sauce over the chicken and vegetables, stirring constantly until the glaze is thick and glossy.
In a separate small pan, lightly steam or sauté the cauliflower rice for 2 minutes until just tender.
Divide the cauliflower rice into bowls and top with the sweet and sour chicken stir-fry.