Preheat oven (electric cooker: 200 °C/ circulating air: 175 °C/ gas: level 3). Clean, wash and cut the peppers into pieces. Peel and finely chop the onion. Heat oil in a pan.
Sauté onion and paprika for about 5 minutes, season with salt, pepper and thyme. Wash the cod, dab dry and sprinkle with lemon juice. Season with salt and pepper. Mix sour cream and milk.
Season with salt and paprika powder. Put the paprika in an ovenproof dish. Place fish on top and pour sour cream over it. Put the baking dish in the oven and cook for 12-15 minutes. Garnish with thyme. Delicious with baguette.