Peel the potatoes and wash them thoroughly. Peel the shallots and cut them in half or quarters as desired. Wash thyme, shake dry, put 4 stems aside for garnishing and pluck the leaves from the remaining stems. Wash the meat and dab dry.
Cook the potatoes in boiling salted water for about 25 minutes. At the same time heat 2-3 tablespoons of oil in a pan, fry two steaks on both sides. Season with salt and pepper, remove from the pan and place on a baking tray. Process the remaining two steaks in the same way. Then cook in a preheated oven (electric cooker: 150 °C/ convection oven: 125 °C/ gas: see manufacturer) for 20-25 minutes.
Add 2 tbsp. oil and 10 g butter to the frying fat, heat, add shallots and fry while turning. Add thyme leaves, dust with sugar and allow to caramelize slightly. Deglaze with stock and vinegar, bring to the boil and simmer over a low to medium heat for 18-20 minutes. Then season to taste with salt and pepper.
At the same time peel garlic and cut it into slices. Heat 1 tablespoon of olive oil in a small pot and roast the garlic in it. Heat the milk, 5 tbsp. olive oil and 25 g butter in a small pot
Drain the potatoes, add hot milk mixture and mash with a potato masher. Take the meat out of the oven and let it rest for a short time. Arrange meat, sauce garnished with thymain and mashed potatoes sprinkled with garlic on plates