Lightly toast the chicken breast together with the onion in oil or margarine. Add the mushrooms and bell peppers and cook for about 5 minutes. Dust with sweet paprika, add ketchup. Season with salt and pepper. If necessary, add a little chicken stock and simmer gently for about 10 minutes until the juice thickens a little.
In the meantime, stir the cream with a little flour until smooth. Tie the sliced meat with the cream and flour mixture and let it steep for a moment.