Heat oil in a skillet set over medium-high. Season chops with salt and pepper. Brown well and set in your slow cooker. Add mushrooms and onion to the skillet and cook until tender, about 5 minutes. Mix in the garlic, flour and sage; slowly mix in stock. Bring the sauce to a simmer, and then pour over the pork. Cook on the low setting 8 hours. Plate the chops, top with sauce, garnish, if desired, and serve.
Note: This recipe is designed for an oval-shaped slow cooker with a 5 litre or more capacity.