Whisk the tomato paste, coconut aminos, apple cider vinegar, and honey in a small bowl until smooth to create the sweet and sour sauce base.
Season the diced chicken breast evenly with the sea salt and black pepper.
Heat the toasted sesame oil in a large skillet or wok over medium-high heat.
Add the chicken to the skillet and sear until golden brown and cooked through, then remove the chicken and set it aside on a plate.
In the same skillet, add the red onion and bell pepper, sautéing for 3-4 minutes until they are tender-crisp.
Stir in the minced garlic and grated ginger, cooking for 1 minute until fragrant.
Add the pineapple chunks and the cooked chicken back into the skillet with the vegetables.
Pour the prepared sauce over the mixture and toss constantly for 1-2 minutes until the sauce thickens and coats every ingredient.
Steam the cauliflower rice in a separate pan or microwave until tender, then serve the chicken mixture immediately over the warm cauliflower rice.