Prepare Chicken: Clean the chicken breast fillets and dice them into small, evenly sized cubes to ensure even cooking.
Make Marinade: In a bowl, combine banana ketchup, brown sugar, sprite (or 7up), rice wine vinegar, soy sauce, lemon juice, crushed garlic, and a pinch of salt. Mix gently until the brown sugar dissolves.
Marinate Chicken: Add the diced chicken into the marinade and mix well to coat all pieces. Cover with cling wrap and refrigerate for at least 1 hour. Optionally, leave uncovered for best results.
Prepare Skewers: Soak bamboo skewers in cold water for 15-20 minutes to prevent burning during grilling.
Thread Chicken: Thread about four pieces of marinated chicken onto each skewer, leaving a small gap between pieces.
Simmer Remaining Marinade: Pour the leftover marinade into a small saucepan and simmer on low heat for 8-10 minutes until thickened. This will be used as a basting sauce and served on the side. Ensure it is fully cooked to eliminate raw chicken bacteria.
Preheat Grill: Preheat the grill to a medium-high heat and spray with cooking oil to prevent sticking.
Grill Skewers: Place the chicken skewers on the grill and cook for 6-8 minutes total, turning after 3-4 minutes. Baste generously with the thickened marinade during grilling.
Serve: Once the chicken is cooked through and firm, remove from grill and serve with the remaining marinade sauce on the side.