Since this is such a simple recipe, be sure to use a good European-style butter for the best flavor. Sole meuniere, as Julia Child and Jacques Pepin cooked it on their PBS show, used sole that was skinned, trimmed and cleaned, but otherwise left whole on the bone. Julia preferred the fish completely skinned, but Jacques liked to leave on the scaled white skin (the fish's gray skin was removed). To make it easy to serve, we're making it with the fish already portioned into fillets. Dover sole, their preferred fish, is difficult to obtain, but gray and lemon sole are good substitutes.