Brush a nonstick skillet with olive oil. Dip fish in flour and shake off excess. Heat skillet until hot. Add fish and saute, without moving, until it just sets and turns a bit golden, 1 to 2 minutes. With a spatula, flip the fish over to the other side and cook until the fish is firm and cooked through, about 2 minutes. Remove fish to dinner plates Add water lemon juice and zest to skillet and increase the heat to medium high. Scrape up browned bits on bottom of pan and boil until syrupy about 2 minutes. Remove skillet from the heat and swirl in butter and parsley. Season with salt and pepper and spoon over fish. Serve with steamed sugar snap peas or other vegetable. French bread on the side would be lovely.