For the fillet steaks, heat 2 tablespoons of oil in a frying pan. Dab the meat dry and fry it in the hot oil for about 2 minutes on each side. Season with salt and pepper. Remove from the pan (keep frying fat in the pan), place on a baking tray lined with baking paper.
Bake in a hot oven (electric cooker: 100 °C/circulating air: 75 °C/gas: see manufacturer) for about 15 minutes until pink.
For the mushrooms in the meantime, wash the lemon hot, dry it and finely grate the skin. Dice bacon finely. Clean the mushrooms and wash them briefly if necessary. Cut mushrooms into thin slices. Wash and pluck thyme.
Fry the bacon in the frying fat until crispy and take it out. Heat 2 tablespoons of oil and butter in a frying pan. Sauté the mushrooms well (see tip). Add lemon zest and thyme and fry briefly. Season mushrooms with salt and pepper.
Add bacon again. Arrange steaks and mushrooms. Mashed potatoes go well with it.