Toss chicken, onions, and tomatoes in the marinade. Marinate in the refrigerator, covered, for at least 20 minutes and up to one day. If using bamboo skewers, soak in warm water for 30 minutes before using to avoid splintering.
Place chicken, onion, tomatoes, pineapple (if using), and plantains on a skewer. Leave space at both top and bottom of the skewer. Sprinkle each skewer all around with salt and pepper.
Preheat oven to 425 degrees. Line a baking sheet with parchment or foil. Place skewers on sheet and roast for 30 minutes, rotating sheet pan, and turning over skewers halfway through. Baste with leftover marinade halfway through.
Oil the grates of the grill and set the grill to medium heat. Use marinade for basting while cooking. Cook for about 15 minutes, turning to grill each side. Enjoy!