Marinade: Whisk together white vinegar, brown sugar, salt, sugar, garlic powder and orange zest until well-mixed; add chicken pieces. Soak chicken pieces in the marinade mixture for 30 minutes, moving them to the refrigerator to keep cool.
Grill Chicken: Remove chicken from brine and pat dry with a paper towel. Place on a hot grill at 400F (gas or charcoal work well). Watch the chicken as it cooks. When it starts to appear white around the edge, it is getting done and is ready to be flipped over so that the other side can cook. Cook until a meat thermometer inserted at the thickest part reads 165F.
Toast Buns: For the last few minutes, while the chicken is still on the grill, spread soft butter on both halves of the bun. Warm them on the grill face down. It doesn’t take long for them to brown, so be sure to watch them attentively.
Chick-fil-a grilled chicken club sandwich assembly: Now that the chicken is grilled and the buns have been toasted, you’ll want to assemble the delicious sandwiches right away, so they can be served hot. On the toasted bun, add lettuce, thin slices of tomato, a slice of Colby Jack cheese and any desired condiments. We recommend Chick-fil-A sauce. Mayonnaise is also a good alternative solution.