For the filling, peel and wash the potatoes and cut them into 1 cm pieces. Heat 2 tablespoons of oil in a frying pan. Fry the potatoes over medium heat for about 15 minutes while turning. Chop the olives.
Wash, halve, seed and dice the tomatoes (put tomato seeds aside for the sauce). Stir olives, tomatoes, crème fraîche and breadcrumbs into the potatoes. Season to taste with salt and pepper.
For the sauce, peel onions and garlic and dice finely. Fry 1 tablespoon of oil in a pot until translucent. Add tomatoes with juice, 1 tsp. cumin and 1 tsp. oregano. Simmer for about 10 minutes, crushing the tomatoes with a wooden spoon.
Season to taste with salt and pepper. Put into an ovenproof dish (approx. 20 x 30 cm).
Cut the bell peppers into a T-shape (alternatively: halve the bell peppers lengthwise). Carefully remove parting skins and seeds. Wash the bell peppers.
Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Carefully fill the peppers with the potato mixture. Place on the tomato sauce with the opening facing upwards. Cover with aluminium foil and cook in the hot oven for 25 minutes.
Remove foil and continue cooking for about 15 minutes.