In a 12x8 inch baking dish, layer half of potatoes and 1/2 can French fried onions. Top with mushrooms and remaining potatoes.
In another pan, melt butter; stir in soy sauce, mustard, cayenne pepper sauce and garlic powder. Brush half of soy sauce mixture over potatoes.
In a large skillet, heat oil. Brown pork chops; drain. Arrange chops over potatoes and brush with remaining soy sauce mixture. Bake, covered, for 1 hour. Bake, uncovered, for an additional 15 minutes or until chops and potatoes are done. Top chops with remaining onions; bake, uncovered, 5 minutes longer or until onions are golden brown.