In early spring, the leeks and spinach from the farmers market are unbelievably sweet and delicious. The spinach has none of that slight taste of minerals that it will later have, and it’s available in abundance. Combined with local mushrooms and locally fished flounder, they made for a flavorful and healthy supper.
I have been asked a few times for simple ways to make a foolproof fish dish, and this is one. I cook the three vegetables one at a time in the same pan to avoid too much cleanup. I’ve made this twice in the past two weeks. The first time, I combined the spinach, leeks and mushrooms as a base, reserving some of the mushroom-leek mixture to scatter on top with tarragon. The second time, spinach alone made the base and the topping of leeks, mushrooms and tarragon nearly smothered the fish and kept it moist during its time in the oven. This dish feels very clean and healthy for this time of year.
Baked White Fish with Spinach, Leeks and Mushrooms
½ lb flounder or sole (3-4 small pieces) or fluke flounder (1 piece)
1 bunch spinach
6-8 cremini mushrooms
Fresh green herbs: tarragon, parsley, dill or lovage, or a combination
Preheat the oven to 350 degrees. Lightly butter a baking dish that will just hold the fish in one layer.
Stem the spinach and wash the leaves well. Shake them to remove excess water and wilt them in a large pan on top of the stove. Remove the spinach to a colander to cool and drain. Wipe out the pan since you’ll use it for the leeks and then the mushrooms. When the spinach is cool, squeeze out the excess moisture and place the leaves in the bottom of the baking dish (you can slice the leave if they’re very large). Place the fish on top.
Slice the white and light green part of the leek lengthwise and clean well. Slice it crosswise into thin slices. Melt a small bit of butter (a teaspoon or less) in the pan and place it over medium-low heat. Saute the leek lightly until coated with butter. Add a teaspoon of water and cover the pan. The leek will cook until tender in a couple of minutes. Spoon it over the fish.
Wipe the mushrooms with a cloth to remove any loose dirt, trim the stem if necessary, and chop them in to 1/4-inch cubes (or slice them thinly). Add another teaspoon of butter to the pan, turn the heat to medium-high, and cook the mushrooms in one layer until lightly browned on one side. Toss to cook for another minute, and add to the leeks on top of the fish. Add a few chopped herbs.
Bake in the oven until the fish is cooked through, about 10 minutes. Let the dish sit for a minute or two after removing from the oven to let the fish firm up a bit.
Alternative: add most of the leeks and mushrooms to the spinach base and scatter the rest on top before baking.