Poached halibut with mustard sauce

I've had a hankering for halibut for several weeks. When we went to Pesce a few weeks ago, I was dreaming of the poached halibut they serve there, but it wasn't on the menu that night. When we visited friends at Beach Haven in September they said their fishmonger was bringing them halibut from the market on Long Beach Island, but he came back with grouper instead. At Rehoboth over the weekend, the restaurant where we had dinner had a halibut special but I didn't like the accompaniment (and someone who ordered it left the sides on the plate).

It turns out it's not that hard to poach halibut and this recipe from Mark Bittman fully satisfied my craving. Although he says this Dutch recipe works for any North Atlantic white fish, he thinks poaching is the best way to cook halibut to keep it from drying out. This comes out creamy and delicate and the understated mustard sauce does not overpower the sweet fish flavor.

For some reason, Bittman always specifies halibut steaks for his recipes, whereas we prefer fillets and that's what The Fishery sells. So I got a nice piece of fillet with the skin on and used the recipe's third option for poaching liquid -- 4 c. of water and white vinegar on an 8:1 ratio (the other two options were Court Bouillon or Fast Fish Stock). It did the trick and is a great option for a weekday meal. Bring the liquid to a boil in a skillet just large enough to hold the fish, put the fish in, adding more liquid to cover if necessary, and simmer at medium low until opaque throughout.

The fillet was not the same thickness and my skillet was too shallow for the thickest part, so I had to carefully turn the fish as it cooked. But this gave me a chance to remove the skin.

For the sauce, cook 1 Tbl flour in 1 Tbl butter for 3 or 4 min until brown, then add 1 c. of the poaching liquid. Cook and thicken for another 4 to 5 min. then add salt and pepper and 1 Tbl Dijon mustard. Serve the sauce over the halibut and sprinkle with chopped parsley.

Bittman recommends boiled potatoes to accompany (it is a Dutch recipe, after all), but we had lentils. I used a preparation I found in an Epicurious recipe (from Gourmet) for Sauteed Cod with Lentils. It calls for French green lentils, and we used the Zursun Idaho heirloom lentils that we bought at La Cuisine in Alexandria. Bring 1 c. lentils to a boil and cook 12 to 25 minutes until tender, then drain, reserving the liquid. Cook 1 c. chopped onion and 1 chopped garlic clove in 2 Tbl. butter in a covered pot for 10 min., stirring occasionally, then uncover and cook another 5 or 10 min. Add the lentils and 1/4 to 1/2 c. of their cooking liquid to moisten, heat through, then add 1 Tbl. lemon juice, 3 Tbl. chopped parsley and 1 Tbl. olive oil. Lentils were delicious and paired perfectly with the halibut.