In a large skillet, cook beef and onion over medium heat until meat is no longer pink; drain. Stir in tomato sauce and taco seasoning. Bring to a boil. Reduce heat; simmer, uncovered, for 5 minutes.
Meanwhile, separate crescent dough into eight triangles; place in a greased 9-in. pie plate with points toward the center. Press onto the bottom and up the sides to form a crust; seal perforations.
Sprinkle 1 cup chips over crust. Top with meat mixture. Carefully spread sour cream over meat mixture. Sprinkle with cheese and remaining chips. Bake at 350° for 20-25 minutes or until cheese is melted and crust is golden brown. Let stand for 5 minutes before cutting.