Season your chicken with salt and pepper. Turn on your Spark and preheat to 500°F. Coat the grates with a high heat cooking oil.
Grill your chicken strips until browned and cooked through, about 5 minutes on each side. At the same time, grill your tomatoes on the vine until skins start to split and grill the jalapeños until nicely charred. Remove everything from the grill and let the chicken cool before shredding into bite sized pieces. Chop or slice the jalapeños.
Cover the bottom of an aluminum pan with a layer of chips, then half each of the chicken and cheese. Repeat the layering of chips, chicken and cheese. Place the entire pan on the grill and close the lid. Cook for about 8-10 minutes or until the cheese is melted.
Remove from the grill and top with the tomatoes, sliced avocado, scallions and cilantro. Serve with sour cream and salsa on the side if desired.