Spinach wash, clean. Peel garlic and onion. Wash rosemary, shake dry, except for something to garnish, pluck needles from the twigs and chop. Wash meat, dab dry, season with pepper, rosemary and a little salt.
Wrap with bacon. Heat 1 tablespoon of oil in a pan. Fry the meat for about 5 minutes, turning it over. Peel potatoes and cut into cubes. Cut garlic into slices. Put the fillets on an oiled baking tray.
Mix potatoes with garlic and season with salt and pepper. Spread around the meat on the tray and drizzle with 2 tablespoons of oil. Add the remaining rosemary. Cook in the preheated oven (electric cooker: 150 °C/ convection oven: 125 °C/ gas: level 1) for 20-25 minutes.
In the meantime, finely dice the onion. Heat 1 tablespoon of oil and sauté the onion until translucent. Add the spinach, sauté briefly, pour on the stock and steam in a closed pot for about 5 minutes.
Season to taste with salt and pepper. Cut meat into slices and arrange on plates with potatoes and spinach. Garnish with rosemary.