Preheat the oven to 375 degrees . In a large skillet, heat the oil over medium heat. Add the chicken and cook, turning once, until cooked through, 10 to 12 minutes. Let stand until cool, then shred the meat into a large bowl. Stir in the salsa, kidney beans, onion and sour cream.
Grease a 9-by-13-inch baking dish, scatter 1 cup tortilla chips on the bottom and top with half of the chicken mixture and half of the cheese. Repeat the layers and cover with the remaining 1 cup tortilla chips. Bake until the cheese is bubbly, about 30 minutes.