Grease four small moulds or one large mould. Peel the potatoes and cut them into thin slices. Lay out the forms or moulds in a fan-shaped manner in three layers. Season milk and cream with salt, pepper and nutmeg.
Pour over the potatoes. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 35 to 45 minutes. Wash, clean and halve the beans. Cook in little boiling salted water for 15 minutes.
Wash and clean the tomatoes. Halve the chillies, scrape out the seeds. Wash the pod and chop very finely. Mix with the soy sauce. Wash the meat and dab dry. Rub a large pan with oil, heat it up.
Fry the fillets for four to six minutes while turning. Fry the tomatoes the last minute. Season everything with salt and pepper. Take the pan off the heat. Drain the beans and let them drain. Drip vinegar on the fillets.
Serve gratin with the meat, beans and tomatoes. Add the soy sauce. Dip the beans into it during the meal or drizzle the sauce over them.