The key to this dish are nicely browned apples with enough salt and pepper to balance their tangy sweetness. For this to be achieved, be sure that you have a good hot pan with enough fat to almost fry the apples. And then hold your nerve, don’t stir often. Let them brown in the fat and then stir to brown the other side. Cutting the apples into a larger dice helps ensure that the outside will caramelize before the apples are fully cooked through. Ideally the apples will get a brown crust and still have a bit of bite in the center. I think it is worse to sacrifice the brown crust of the apple than to cook the apples through. Also, use more black pepper than you think you need and, if possible, grind it right then. The spice of the pepper cuts the sweet of the apples and perks up the dish with a bit of heat.