Melt the butter over medium heat (about 1 minute). Add the diced onion and sliced carrots, sauté for 4-5 minutes until softened. Sprinkle the flour and curry powder over the vegetables, stir, and cook for 1 minute. Pour in 500 ml water and stir in the 3 teaspoons instant vegetable stock. Bring to a simmer and cook for 15 minutes.
Squeeze out excess water from the soaked bread roll. Mix the minced meat, egg, and squeezed bread roll together. Season with salt and pepper. Shape the mixture into small balls. Heat the 2 tablespoons oil over medium-high heat in a separate pan and fry the meatballs for 5-7 minutes, turning occasionally, until cooked through (internal temperature 74°C / 165°F).
Stir the crème fraîche into the carrot sauce. Season with salt and pepper. Add the cooked meatballs to the sauce and heat through for 2-3 minutes. Sprinkle with the chopped parsley before serving.