Throughout my years as a chef, this is the best grilled chicken sandwich recipe I've found. I really like the Mexican-style flavors in this all-American grilled chicken sandwich — especially when you add the melted pepper jack cheese, sliced fresh avocado and crispy onion-cheese kaiser rolls. Next time you're going to have an outdoor barbecue, try this recipe out, topped with my Southwest sauce. I think you'll discover that it's one of the most delicious grilled chicken sandwich recipes out there.