1/2 cup homemade or store-bought fish or vegetable stock
Coarse salt
3/4 cup finely chopped fresh flat-leaf parsley
plus 4 sprigs
for garnish
2 tablespoons finely chopped fresh chives
1 strip lemon peel (3 inches)
1/4 cup plus 2 teaspoons fresh lemon juice (about 2 lemons)
4 cod fillets (5 ounces each)
skinned
Instructions
Melt the butter over medium heat in a small saucepan.
Add the flour; whisk until a paste forms.
Reduce heat to low; cook, whisking, 2 minutes.
Whisking constantly, pour in the milk in a slow, steady stream; whisk until incorporated.
Whisk in the stock.
Add 1/2 teaspoon salt, and cook, whisking occasionally, 10 minutes.
Remove from heat; let stand 10 minutes to thicken slightly.
Stir in the parsley and chives.
Meanwhile, bring 1 1/2 quarts water, the lemon peel, 1/4 cup lemon juice, and 1/2 teaspoon salt to a boil in a medium saute pan or other wide straight-sided pan.
Place the fillets in the liquid (do not crowd).
Return to a boil, then immediately turn off the heat.
Let stand until just cooked through, about 10 minutes.
Reheat the sauce over medium-low heat, if necessary, and add the remaining 2 teaspoons lemon juice.
Gently lift the fillets from the liquid with a slotted spatula; place 1 fillet on each of 4 plates.
Spoon one-quarter of the sauce over each serving, and garnish with a parsley sprig.