In a resealable bag or container, whisk the coconut aminos, rice wine vinegar, salt, sesame oil, garlic powder and ginger powder.
Reserve ¼ cup of the marinade and set aside to use later.
Cut the chicken into approx. 1" cubes and add to the marinade, tossing to coat evenly. Marinate the chicken for an hour or up to 36 hours in the fridge, tossing the chicken at least once halfway through to make sure it marinates evenly.
Bring the chicken to room temperature before cooking.
Heat a gas grill or grill pan to medium-high heat. Grease the grill grates or grill pan with avocado oil.
De-seed and chop the pepper into roughly 1" pieces.
Trim off the top and bottom of the pineapple. Then standing it up on one flat end, use your knife to slice down the sides of the pineapple to remove the brown outer layer. Then cut down through the pineapple flesh, keeping your knife blade to the side of the core. You should end up with long slabs and spears of pineapple. Discard the top, bottom, peel and core.
Cut the pineapple into cubes slightly smaller than 1" (if they're the same size as everything else, they tend to actually be too big in comparison).You should need about 2 cups of pineapple. If you have more than that, keep any extra separate. You don't want to contaminate it with the raw chicken juices. Thread the chicken, peppers, tomatoes and pineapple onto your skewers (see notes), repeating until the skewer is almost full. Repeat this until all your skewers are used up. Discard any remaining marinade.
Place the skewers on the grill (and cover them) or grill pan and let them grill (don't move them!) for about 3-5 minutes per side, until they have char marks on the bottom. (We're intentionally slightly undercooking them so we can finish cooking them with the glaze at the end).
Rotate each skewer 180° and grill the other side for about another 3-5 minutes.
While they grill, in a small mixing bowl, whisk the arrowroot into the reserved ¼ cup marinade.
Brush the skewer with the arrowroot/marinade mixture and let it cook for another minute or so.
Flip the skewers one last time, brush with more marinade and grill for another minute or so.
Remove the skewers from the heat, sprinkle with the sesame seeds and enjoy!