Wash the potatoes and cook in boiling water for about 20 minutes. Melt the fat in a saucepan. Sweat flour in it. Add milk while stirring. Stir in stock, bring to the boil and simmer for 5 minutes. Season to taste with salt and pepper. Wash the smoked pork, dab dry and cut into cubes.
Heat oil in a pan. Fry the pork loin briefly. Drain potatoes, rinse and peel. Pour potatoes, cured pork loin and sauce into a greased ovenproof dish. Sprinkle with cheese and bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 10 minutes. Garnish with chives