Chop the onion into small cubes. Heat the fat in a pan and allow the onion to turn translucent. In the meantime, season the minced meat with salt and pepper, add to the onion and roast vigorously. Mix the tomato paste with a little water and pour over it, braise vigorously for a few minutes.
Add the thawed Brussels sprouts and let them get hot over a low heat.
Finally, stir in the sour cream or crème fraîche and season again with paprika, salt and pepper.