Cut the meat into large pieces. Place in a large pot and rinse until the water is completely clear. Leave enough water to just cover the meat.
Cut the carrots and parsnips into large cubes and add to the large pot together with the meat. Cover with a lid and leave to simmer for about an hour and a half.
Skim the surface so that the broth is clear. Taste the meat, if it falls apart in your mouth it is done. Remove the meat and vegetables and reduce the broth over a high heat until about 1¾ cup (350 ml) remains.
The sauce: Melt the butter and stir in the flour. Mix in the lamb broth and cream. Leave to simmer for 10 minutes. Flavor with white vinegar and a pinch of sugar, salt, and pepper. Add the cooked lamb and vegetables and slowly heat the stew.
Serve with boiled almond potatoes or red potatoes.