Brush the black salsifies vigorously under cold water. Cook unpeeled in a wide pot in water for about 20 minutes. Take out, let it cool down a little, remove the skin. Clean the mushrooms, wash them if necessary and cut them into slices.
Peel and finely chop the onion. Wash the chicken filet, dab dry and cut into cubes. Fry all around in 1 tablespoon of hot oil. Fry the onion briefly. Season with salt and pepper, take out.
Fry the mushrooms in the cooking fat until golden brown. Season with salt and pepper. First deglaze with white wine, then with stock and cream, bring to the boil and thicken with sauce thickener. Stir in peas and cook for about 5 minutes.
Add the meat to the sauce and heat. Season to taste with salt and pepper. Whisk Eoer. Turn the black salsifies first in flour, then in egg and finally in breadcrumbs. Heat 4-5 tablespoons of oil. Fry the black salsifies in this mixture in portions all round for about 3 minutes until golden brown.
Serve with the chicken ragout. Serve garnished with lemon and parsley if desired. Boiled potatoes taste good with it.