This dish is a staple at Mabel Gray in the winter months. Fluke is an amazing Atlantic flat fish with delicate white flesh that cooks quickly and easily. Although fluke and beurre blanc seem very French, the hard char on the potatoes and cabbage and the big dose of whole grain mustard give it some North American gusto. I think this dish is a great representation of Montréal cuisine.
First, the fish.
Ask your local fish monger for a skinned fillet of fluke. About 5-6 oz a person is plenty. You could use halibut or John Dory if you must, but I prefer fluke.
The potatoes.
I recommend using about 4-6 fingerlings per person. You should par bake them at 350° until tender (maybe 20-30 minutes). Once slightly cooled down to warm, use the palm of your hand and gently smash the potato about half way. Don’t make it a pancake. Just break it and press it a little. This will allow the center flesh of the potato to get crisp and textural when frying again in a cast-iron.
The cabbage.
I like to use savoy cabbage. The crinkly green one. Peel off any outer layers that do not look fresh and clean. Split the cabbage in half and cut out the core. Cut the cabbage in rustic strips about two inches wide. Set aside.
The sauce.
Beurre blanc is made in a couple different ways. Traditionally, you’re simmering white wine down with aromatics (shallot, peppercorn, bay leaf, maybe thyme) until reduced nicely and then emulsifying room temperature whole butter into it, seasoning with a little salt and lemon and voila. Clean, classic beurre blanc. A short cut/hack is to add heavy cream halfway through the reducing of the white wine and allow the cream to reduce as well. This stabilizes the sauce and makes it creamier, which is probably more to the American palate. For a traditional dish, I’d say no way to the cream. But for this wintry mustardy preparation I’m cool with it.
In a sauce pan:
Reduce 1 bottle of clean white wine (like a Chablis) by half.
Add 2 cups of heavy cream. Reduce by half.
While the wine & cream reduction is still hot, whisk in 1 lb of whole butter until fully emulsified and the butter is completely melted into the sauce.
Whisk in 1 cup of high quality whole grain mustard.
Season with fresh squeezed lemon, Tabasco and salt. I like my sauces seasoned heavily. But to each their own. Set your sauce to the side on the stove. Maybe plastic wrap the top of the saucepan and put a lid on it.
The build.
Heat a high quality cast iron pan on the stove. I use the 12” Smithey and swear by it. Add a tablespoon of olive oil when the pan is nice and hot. Add the cooked and gently smashed potatoes and the cabbage. Let brown on one side and add a few tablespoons of butter. Flip the potatoes and the cabbage, allowing to sear hard on the initial side. Once the potatoes are hot and crispy and the cabbage is charred, remove them from the pan and onto a plate lined with paper towel. Drain the fat off the cast iron and wipe out with some paper towel. Don’t burn yourself doing this. Allow the pan to get hot again.
Season the fluke with a nice amount of kosher salt on both sides. Add a couple tablespoons of olive oil to the pan and once almost smoking add the fluke to the pan.
It is very important to let the fluke brown. Don’t agitate it. After a minute or so add a few tablespoons of warm butter and a couple sprigs of fresh thyme. Move the butter around the pan and maybe baste the fish a little. Use a fish spatula to take a peak at the fluke to see if it’s starting to brown. If browned, flip the fluke gently using the fish spatula. Let cook for a minute or so and then remove the fish and transfer to a plate lined with paper towel.
On a large dinner plate or platter, place the potatoes flat in the center of the plate. Add half the cabbage on top of the potatoes. Then gently place the fish on top of the cabbage. Take the remaining cabbage and drape it over the fish decoratively. Then ladle a ton of the beurre blanc all over the whole situation smothering everything. Top with a ton of thinly cut chives. Serve this with ice cold champagne and eat it like it owes you money.