1. Slightly beat egg using a fork. Coat pork chops in the egg mixture.
2. Slice onion into quarter rings. Place sour cream in a separate bowl (if it's too thick, add 1 tablespoon water).
3. In a skillet, heat 1 tablespoon oil. Brown the meat over medium-high on both sides.
4. In a separate skillet, heat 2 tablespoons oil. Add onion and mushrooms, cook for about 7 minutes.
5. Preheat oven to 370 degrees F (190 degrees C).
6. Season the pork chops with salt and pepper to taste. Arrange them in a baking dish.
7. Top the chops with the mushroom mixture.
8. Pour sour cream over the chops.
9. Bake for about 30-40 minutes, or until chops are cooked through.