Heat a high pan and add oil, should be about 1 cm high. Fry all the peppers all around, they should get a strong color, then drain on a plate, preferably on kitchen paper.
Drain the oil, leave only 4-5 tablespoons in, fry the onions in it. Add chopped garlic and fry everything until golden brown, then pour the strong vegetable stock and simmer for 5 minutes. Stir in sour cream and cream and season with salt, pepper and sugar, place the roasted peppers in the sauce and slowly simmer together for about 20 minutes. Season again to taste and, if necessary, spice up.