Step 1

Preheat oven to 425°F. Toss together potatoes, shallots, 1 tablespoon of the oil, and 1⁄4 teaspoon of the salt on a large rimmed baking sheet. Arrange mixture in an even layer, with potatoes facing cut sides down. Roast until almost tender, about 15 minutes. Remove from oven.

Step 2

While potato mixture roasts, stir together 3 tablespoons of the mustard, 1⁄4 teaspoon of the salt, and 1 teaspoon of the honey in a small bowl. Stir together panko, thyme, 1 tablespoon of the oil, and 1⁄4 teaspoon of the salt in a separate small bowl. Arrange salmon fillets, skin side down, on a plate. Spread mustard mixture evenly over skinless tops of fillets. Sprinkle tops evenly with panko mixture, pressing to adhere.

Step 3

Stir roasted potato mixture on baking sheet, pushing mixture toward edges of baking sheet with a spatula. Place salmon filets, skin side down, in center of baking sheet. Scatter sugar snap peas evenly around salmon. Return baking sheet to oven. Bake at 425°F until panko crust is golden brown, salmon is cooked to medium doneness (turns flaky and opaque), and potatoes are tender, about 10 minutes.

Step 4

Meanwhile, whisk together vinegar, garlic, smoked paprika, and remaining 2 tablespoons oil, 1⁄4 teaspoon salt, 2 teaspoons mustard, and 1⁄2 teaspoon honey in a small bowl until combined.

Step 5

Divide salmon fillets and vegetable mixture evenly among 4 plates. Drizzle vegetable mixture evenly with vinaigrette.