Heat oven to 350 degrees. Coat both sides of each pork chop in prepared mustard, and then coat with flour.
Melt butter in skillet, then sear each side of the pork chops for approximately 1 minute or until golden brown.
Transfer pork chops into bottom of a 9 x9 inch baking dish. Add both cans of Chicken and Rice soup to cover.
In the same pan that the pork chops were browning in, sautee the onion slices until translucent and golden brown. Spoon the onions over the pork chops.
Cover and bake for 1 hour at 350 degrees. Remove cover for the last 5 minutes of baking.