For the egg whites, wash the parsley and chop very finely, except for a few leaves. Whisk eggs, milk and parsley. Season to taste with salt and nutmeg. Pour into a greased mould.
Leave to stand in a hot water bath for about 20 minutes. In the meantime, cut tomatoes crosswise. Scald with boiling water, remove skin. Cut tomatoes in half, remove seeds. Cut tomato flesh into small cubes.
Clean, wash and slice the mushrooms. Heat oil in a pot. Briefly sauté the mushrooms in it. Add 1/2 litre water and the bouillon. Bring to the boil. Season to taste with salt and pepper if necessary.
Cut the egg stitch into rhombs. Add egg rhombs, diced tomatoes and remaining parsley leaves to the broth.