Season the chops with salt and pepper and sauté. Remove the chops from the pan and keep them warm.
To make the Pan Sauce: Pour off all but 1 tbsp of the fat from the pan and cook the onion, covered, over medium heat for 5 minutes, stirring occasionally. Add the stock, juice, and pineapple, scraping up any browned bits from the bottom of the pan. Boil the sauce down for 3 minutes. Thicken it slightly by whisking in the cornstarch just before serving. Pour over the chops and serve.