Place the chicken stock in a 6-quart kettle and put it on the heat.
In a small frying pan sauté the onion in the butter or oil just until clear. Stir in the flour and cook for a moment, thus making a roux.
Stir the roux into the hot soup stock, stirring until the soup thickens a bit. Add the potatoes and bay leaf and cook until the potatoes are tender. Remove the bay leaf. Add the half-and-half and the corn. Bring to a simmer and season to taste with salt and pepper. Finally, add the crawfish meat and heat for just a moment.
Serve, garnished with the parsley and sliced eggs.
Servings: 4