Mix a beurre manié, by combining the softened butter and flour to make a smooth paste and set aside.
Heat cooking oil in a large sauté pan over medium heat.
Place onion in a pan and cook for a minute or two. Place fish over onions in pan. Add the milk and a few grindings of pepper. Bring milk to a gentle simmer. Reduce heat to medium low, cover pan and cook for about 5 minutes. Remove fish, leaving milk mixture in pan, and let cool for a minute or so. Add green onion to milk in the pan and continue to gently simmer for another 5 minutes.
Meanwhile, cut or break fish into strips about 1-1/2 inches wide and set in a warmed serving dish.
Remove pan with milk from heat—either turn off heat or move pan off burner. Whisk beurre manié into milk and return to medium heat, stirring constantly. Bring milk back to a simmer—it should thicken slightly. Add cheddar cheese and/or corn, if using, and heat for a minute or two to incorporate into sauce. Check sauce consistency and if too thick add milk and heat for a minute. Stir in chopped parsley and pour sauce over reserved fish.
Tracy’s Tasting Notes: It was a challenge to find the perfect wine pair for this traditional dish. After trying a Pouilly Fuisse (too acidic) and a domestic Chardonnay (too overpowering), we settled on an Alsatian blend of Chardonnay, Gewurztraminer and Riesling, which did a much better job in complementing both creamy and salty flavors. Among the tasters, there were two camps, however—some of us at the tasting table felt the best match would really be an ice-cold beer. Try: Now & Zen ‘Wasabi White’ $11.99 or Cape Cod Beer Summer Ale $12 for a 64-oz Growler.
Words by Tracy Anderson