Put the pork loins in a shallow dish and add two spoonful of mustard and one garlic (minced). Mix well, coating well all the chops. Marinate for minimum 30 minutes.
Cut the onion into thin slices and chop the rosemary leaves. Slice the mushrooms.
Heat the oil a large frying pan and gently sauté the onion for five minutes, then add the mushrooms and rosemary.
Put a lid on and cook for 5 minutes.
Move the mushrooms and onions to one side of the pan, then put the pork chops to the other side ( you might want to add a drop of oil). Mix the other garlic and lemon juice into the mushroom mixture. Season everything with pepper.
Put a lid on and cook for 3 minutes, then turn over the chops and cook for another 3 minutes.
Add the remaining mustard to the mushroom, then pour in some water (mixed with a little corn starch), or white wine, or stock. Turn up the heat and reduce the sauce until creamy, while keep turning over the chops to brown a bit (don’t over-cook them!).
Transfer the pork chops to a plate to rest, and reduce the mushroom sauce further, if needed.
Serve the loin chops with the mushroom sauce, parsley leaves scattered on top.