Preheat oven (electric cooker: 200 °C/circulating air: 180 °C/gas: see manufacturer). Line a tray with baking paper. Place bacon slices in one corner of the baking tray next to each other. Wash potatoes thoroughly, dab dry and cut in half horizontally. Distribute on the free tray with the cut surface facing upwards. Season with salt. Bake in a hot oven for 50-55 minutes. Remove bacon from the oven after 10-12 minutes.
Wash the sage, shake dry, pluck leaves. Clean the mushrooms, possibly wash and slice them. Wash tomatoes, cut in half.
Dab the fillet of beef dry and cut into 4 steaks of equal thickness. Wrap each fillet with a piece of kitchen string and season with salt. Heat 3 tablespoons of oil in a frying pan. Sauté the meat in it over a high heat for about 1 minute. Then fry for 3-4 minutes on each side. Fry the sage very briefly, take it out and let it drain on kitchen paper. Season the steaks with pepper, remove from the pan and let them rest in aluminium foil for about 5 minutes.
In the meantime heat 2 tablespoons of oil in the frying fat. Fry the mushrooms until golden brown. Steam the tomatoes briefly at the end. Season with salt and pepper. Break bacon into pieces. Arrange steaks with potatoes, mushrooms and tomatoes. Pluck the burrata and spread on the steaks. Sprinkle with bacon and sage leaves.
Tip: Take the fillet of beef out of the fridge about 1 hour before roasting, it will be more tender.