1. Prepare the Glaze: In a large mixing bowl, whisk together the unsweetened peanut butter, tamari, toasted sesame oil, lime juice, and white vinegar until the mixture is smooth. Stir in the optional sweetener, minced garlic, the white parts of the green onions, chopped cilantro, ground ginger, and salt. Mix until everything is well combined.
2. Marinate the Chicken: Add the chicken cubes to the bowl. Use a spatula to toss the chicken, ensuring every piece is generously coated in the peanut glaze. Cover the bowl and refrigerate for at least 45 minutes, or up to 8 hours for a deeper flavor.
3. Assemble the Skewers: Remove the marinated chicken from the refrigerator. Thread the chicken pieces onto your prepared skewers, packing them together snugly but not too tightly. Divide the chicken evenly among the 8 skewers.

Cook the Skewers (Choose your method):

1. Oven Method: Preheat your oven to 425°F (220°C) with a rack in the upper-middle position. Place a wire rack inside a rimmed baking sheet and brush it lightly with avocado oil. Arrange the skewers in a single layer on the wire rack. Roast for 15-18 minutes, or until cooked through and the edges are beautifully caramelized. The internal temperature must reach 165°F (74°C).
2. Grill Method: Preheat your grill to medium-high heat (400-450°F / 200-230°C). Brush the clean grill grates with avocado oil. Place the skewers on the grill and cook for 4-6 minutes per side, flipping once. The chicken is done when opaque throughout and an instant-read thermometer inserted into the thickest piece reads 165°F (74°C).
3. Serve: Transfer the hot skewers to a serving platter. Garnish generously with the chopped roasted peanuts, the reserved green onion tops, and fresh cilantro leaves. Serve immediately.