Reduce heat to medium, and cook until lightly brown, about 6 minutes.
Add wine, reduce heat to medium, cover, and cook for 5 minutes more.
Turn the fish pieces and reduce the heat to medium.
Reduce the heat to medium and simmer for 20 minutes.
Cook for 3-4 minutes on one side, then reduce the heat to medium.
Reduce heat to medium, cover and steam for 20 minutes.
Reduce the heat to medium and cook until just done, 10 to 15 minutes.
Add the remaining 1/2 cup oil and reduce the heat to medium.
Reduce heat to medium and cook for about 6 minutes more.
Cook the potatoes 2 minutes, then reduce heat to medium.