Season the pork chops with poultry seasoning, salt, and pepper. Toss the pork chops in the flour to coat on all sides.
Heat the olive oil in a large skillet over medium heat. Cook the pork chops until golden brown on both sides, 3 to 4 minutes per side. Set aside on a plate.
Stir the onions into the hot pan, and cook over medium-high heat for 5 minutes, stirring frequently. Stir in the water and butter. Continue cooking and stirring until the onions are soft and a nice golden brown, about 10 minutes.
Once caramelized, stir in the mustard and gravy. Bring to a simmer, then put the pork chops into the pan and cook a bit more to reheat.