How to Make It
In a large skillet, melt the butter over moderately high heat. Stir in the brown sugar, then add the apples in a single layer and cook until golden brown and tender, 3 to 4 minutes per side.
In another large skillet, heat the canola oil over moderately high heat. Season the pork medallions generously with salt and pepper and cook until golden brown all over, about 15 minutes. Transfer the pork to a serving platter and keep warm.
Add the Riesling to the second skillet and cook over high heat until reduced to 1/4 cup, about 3 minutes. Add the stock and simmer until the sauce reduces slightly, about 12 minutes; season with salt and pepper. Add the apples and cook over moderately low heat until warmed through. Pour the apples and sauce over the pork and serve.