Defrost the peas. Cut the bark off the toast. Cut bread into rhombs. Heat 2 tablespoons of oil in a coated pan. Fry the bread in it until golden brown, seasoning lightly with salt and pepper.
Peel and chop the onion. Peel, wash and dice the potatoes. Heat 1 tablespoon of oil in a saucepan, fry the onion and potatoes. Put 1/4 of the peas aside. Add the remaining peas to the pot and sauté briefly.
Deglaze with stock, bring to the boil and simmer covered for about 10 minutes. Puree the soup. Cut sausage diagonally into slices and add to the soup with the remaining peas. Bring to the boil and season to taste with salt and pepper.
Wash parsley, dab dry, remove stalks and chop leaves coarsely. Arrange soup in preheated bowls. Mix crème fraîche and cream. Add the mixture to the soup in streaks. Sprinkle pea soup with croutons and parsley.