Season pork chops with salt and pepper.
In a shallow dish, combine the flour with garlic powder and ground mustard.
Dredge each pork chop in the flour, and shake off any excess.
Heat oil in a skillet over medium high heat, and brown pork chops on both sides until golden brown (work in batches) – about 2-3 minutes per side.
Transfer the pork chops to the slow cooker.
In the same skillet, sauté the onions until translucent (2-3 minutes), then add the garlic and cook for 30 seconds.
Transfer the onions and garlic to the slow cooker.
Pour the chicken stock over the chops. Cover and cook on LOW for 2-3 hours. The pork chops are ready when the internal temperature of the meat reaches 145°F/63°C. Make sure that they don’t cook for too long and dry out.
Remove the pork chops onto a plate, and cover to keep warm.
Thicken the gravy by whisking in flour. Cook covered on HIGH until the gravy has thickened.
Return pork chops into the gravy to mix together. Serve warm with mashed potatoes and salad or steamed green vegetable (broccoli, green beans, broccolini, or asparagus).