Sautéing the fish skin-side down in a covered skillet is a great technique that yields crisp skin and tender flesh without the need for any flour. A mustard and lemon vinaigrette both seasons the fish and dresses the salad.
Fresh dill, 1large bunch, roughly chopped, about ½ cup (½ oz/15 g)
Small fresh basil leaves, ½cup (½oz/15g) packed
Preheat the oven to 425°F (220° C). In a large bowl, toss the potatoes with 1 tablespoon of the oil. Sprinkle with salt and pepper and toss to coat. Arrange the potatoes cut side down on a large rimmed baking sheet. Roast until browned on the cut side and tender, about 25 minutes.
Meanwhile, in a small bowl, combine the mustard and lemon juice. Gradually whisk in ½ cup (4 fl oz/125 ml) of the oil. Mix in the minced green onion to make a vinaigrette, then season to taste with salt and pepper. Transfer 2 tablespoons of the vinaigrette to a small bowl and brush over the flesh side of the fish. In a salad bowl, combine the greens, parsley, dill, basil leaves, and two-thirds of the sliced green onions.
In a 12-inch (30-cm) nonstick frying pan over medium-high heat, warm the remaining 1 tablespoon oil. Add the fish, skin side down. Cover the pan and cook the fish without turning until springy to the touch, about 5 minutes.
Dress the salad with vinaigrette to taste and toss well. Divide the salad among 4 warmed plates. Top with the fish, and then drizzle the fish with a little vinaigrette. Arrange the potatoes alongside and serve right away.