Peel off the dark skin from the sole and score the white skin along the backbone with a razor blade. Cut off fins as well as head and remove innards (or have everything already prepared by the fishmonger). Wash well and pat dry. Rub with a little Worcestershire sauce and salt. Turn in flour and sear in olive oil, first on the stripped side. Once the sole is golden brown (after about 2 minutes), turn and add plenty of butter. Now reduce the heat enough so that the butter foams but does not brown. Cut the peeled, cooked potatoes into bite-sized pieces and add. Using a spoon, keep pouring foaming butter over the fish. After about 5 minutes, stir in the lemon juice and coarsely plucked parsley. Season with sea salt and pepper and serve in the pan.