In a bowl, whisk together olive oil, vinegar, garlic, adobo seasoning, paprika, oregano, black pepper, salt, soy sauce, and ketchup.
Add the chicken pieces and toss to coat evenly. Cover and marinate in the refrigerator for at least 2 hours (overnight for best flavor).
Preheat grill to medium-high heat.
Thread marinated chicken pieces onto soaked skewers.
Grill for about 10-12 minutes, turning occasionally, until chicken is fully cooked and slightly charred.
Optional: Baste with BBQ sauce during the last few minutes for an extra smoky glaze.
Serve hot and enjoy!