Preheat the oven to 210°C.
Peel and slice the potatoes into rounds and cook for 5 minutes in a dish in the microwave with a little water.
Cut 6 rectangles of greaseproof paper (about 30 x 20cm).
Wash and trim the peppers and cut into small pieces. Cut the spring onions into slices.
Chop the garlic cloves. Cook these vegetables on low heat with 100g Elle & Vire unsalted gourmet butter, salt and pepper. Cook for 15 minutes.
Then add the tomato sauce and Elle & Vire cooking cream. Simmer for a few minutes.
Put it all in the food mixer.
Pour the sauce over the greaseproof paper rectangles.
Spread the potato rounds on top; salt, pepper, and add a few knobs of butter.
Salt and pepper the monkfish, place a piece in each papillote before pinning it closed with a cocktail stick.
Bake for 15 minutes.