Ingredients:
Kosher salt and freshly ground black pepper
1/2 cup panko
1/2 cup loosely packed fresh flat-leaf parsley leaves and tender stems
1 sprig of fresh tarragon leaves, plus 2 tablespoons coarsely chopped fresh tarragon
2 tablespoons olive oil
2 teaspoons brown sugar
2 teaspoons Dijon mustard
3 tablespoons fresh lemon juice, plus lemon wedges for serving
Four 6-ounce skinless center-cut salmon fillets (about 1 1/2 inches thick)
1 pound thin asparagus, trimmed and cut into 1 1/2-inch pieces
2 cups shelled English peas or thawed frozen peas (about 10 ounces)
2 tablespoons unsalted butter
4 radishes, thinly sliced (about 4 ounces) (see Cook's Note)
Instructions:
Preheat the oven to 425 degrees F and line a baking sheet with aluminum foil.
Bring 8 cups of salted water to a boil in a covered large saute pan. Fill a large bowl with ice water and set a mesh strainer on the ice.
Pulse the panko, parsley, and leaves from 1 sprig of fresh tarragon and 1/4 teaspoon of each salt and pepper in a mini food processor until the herbs are coarsely chopped. Drizzle in 1 tablespoon of the oil and pulse until the mixture is combined. Transfer to a plate.
Combine the brown sugar, mustard, 1 tablespoon of lemon juice and the remaining 1 tablespoon of oil in a small bowl. Brush the tops and sides of the salmon generously with the mustard mixture and sprinkle with salt and pepper. Press a salmon fillet, top-side down, into the panko mixture. Place, panko-side up, on the prepared baking sheet. Repeat this with the remaining fillets and bake until the panko is toasted and the salmon has been cooked, for 8 to 10 minutes.
Meanwhile, put the asparagus and peas in the saute pan of boiling water and cook until almost crisp-tender, about 3 minutes. Transfer the vegetables to the prepared ice bath with a slotted spoon and let cool for about 1 minute.
Meanwhile, heat a second large saute pan over medium-high heat and add the butter, swirling until melted. Drain the cooled vegetables and add them to the pan. Season with salt and pepper. Cook, stirring occasionally, until tender, 3 to 5 minutes. Remove from the heat and add the radishes, the remaining 2 tablespoons lemon juice, and 2 tablespoons tarragon. Toss to combine, taste, and adjust the seasoning. Serve the salmon with the asparagus salad and a lemon wedge.