The shell fish used for this are not exactly the Dublin prawns, but closely resemble them, both in appearance and flavour, so Dublin prawns can be used as a substitute.
Clean the prawns and soak them in milk for 2 hours. Bring the courtbouillon to the boil, throw in the prawns, simmer till they have turned pink, drain, and remove the claws and set aside. Pick the meat from the shells and also set aside. Pound the shells in a mortar with the butter and rub through a sieve. Mix the courtbouillon with the meat stock, stir in the potato flour, season with salt and pepper, add the prawn butter, made from the shells, the claws and the tails, the yolks of egg, and simmer without boiling. Finally add the sour cream.