Sort the spinach, wash and drain. Preheat oven (electric cooker: 200°C/circulating air: 175°C/gas: level 3). Peel, wash and slice the potatoes. Heat 2 tablespoons of oil in a pan.
Fry the potatoes for about 10 minutes while turning.
Meanwhile peel onion and garlic, dice finely. Clean the chilli, cut lengthwise, remove seeds, wash and chop very finely. Season potatoes with salt and pepper. Fry half the onion briefly.
Place in an ovenproof dish and continue cooking in a hot oven for about 15 minutes.
Meanwhile wash the meat and pat dry. Heat 1 tablespoon of oil in a frying pan. Fry the meat for 4-5 minutes on each side. Season with salt and pepper and remove. Caramelise the sugar in the hot frying fat.
Deglaze with vinegar and 7-8 tablespoons of water, simmer for 1-2 minutes. Stir in chilli. Add fillets and turn in.
Heat the butter in a pot. Sauté the garlic and remaining onion in it. Add dripping wet spinach and sauté for 2-3 minutes until it has collapsed. Season with salt and pepper. Serve everything.