Heat oil in a large skillet over medium-high heat. Cook chops until well browned on both sides. Remove chops and set aside.
Add onion and mushrooms to the skillet and cook until tender, stirring occasionally. Return chops to skillet. Add water, mustard and salt. Raise heat to high and bring to a boil. Reduce heat to low, cover and simmer for 1 hour.
Remove chops to a warm platter. Into skillet add sour cream and heat through (do not boil). Pour sauce over pork chops. Garnish with parsley and serve.