Cut the Comté into thin sticks. Peel onions and cut them into slices. Dab fillets dry and cut lengthwise. Open the meat and season with salt and pepper. Spread the cheese in the middle of the fillets, leaving about 1 cm of edge free. Fold up the fillets again. Lay the bacon slices next to each other, slightly overlapping (length of fillets). Place one fillet each on top, wrap in the bacon and tie with kitchen string
Heat the oil in a pan. Fry the meat and onion slices for 4-5 minutes while turning them over. Remove the meat, place on a baking tray and cook in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 10 minutes.
Take the meat out of the oven and let it rest in aluminium foil for about 10 minutes. Heat the meat again. Deglaze with stock and wine and bring to the boil. Mix starch with a little water, thicken simmering stock with it, season to taste with salt. Wash the salad and shake dry. Season the vinegar with salt, sugar and pepper, fold in olive oil. Cut the fillets into slices and serve with vegetable oil.