For this sheet pan dinner, baby potatoes, red onion, and spring onions get a head start in a hot oven before they're joined by a side of salmon that's been slathered with mustard and drizzled with toasted garlic oil. The salmon cooks alongside the vegetables for a seamless finish.

Ingredient :

• 1 ½ pounds baby yellow potatoes, halved lengthwise

• 1 large red onion, cut into 1/2-inch wedges

• 5 spring onions (about 6 ounces), trimmed and halved lengthwise

• ⅓ cup plus 2 tablespoons extra-virgin olive oil, divided

• 2 teaspoons kosher salt, divided

• ½ teaspoon black pepper, divided

• ¼ cup Dijon mustard, divided

• 1 (2-pound) skin-on or skinless salmon side

• 3 garlic cloves, thinly sliced (about 1 1/2 tablespoons)

• 2 tablespoons chopped fresh tarragon

• 2 tablespoons chopped fresh chives

• Lemon wedges, for serving

Directions :

1. Preheat oven to 425°F. Toss together potatoes, red onion, spring onions, and 2 tablespoons oil on a large rimmed baking sheet; spread in an even layer. Sprinkle evenly with 1 teaspoon salt and 1/4 teaspoon pepper. Roast in preheated oven until vegetables begin to brown, about 20 minutes. Remove from oven, and reduce oven temperature to 325°F.

2. Add 1 tablespoon mustard to vegetable mixture on baking sheet; toss to coat. Push vegetables to long edges of baking sheet. Place salmon, skin side down, lengthwise in middle of baking sheet. Spread salmon with remaining 3 tablespoons mustard; sprinkle with remaining 1 teaspoon salt and remaining 1/4 teaspoon pepper.

3. Heat remaining 1/3 cup oil in a large skillet over medium-high. Add garlic; cook, stirring often, until garlic is fragrant and light golden brown, about 2 minutes. Pour hot oil mixture over salmon on baking sheet. Roast at 325°F until salmon flakes easily with a fork and vegetables are tender, 12 to 15 minutes. Remove from oven. Transfer salmon to a platter; sprinkle with tarragon and chives. Transfer vegetables to a bowl. Serve salmon and vegetables with lemon wedges.