- 1 pound small new potatoes (about 10), halved
- 8 ounces button mushrooms
- 3 tablespoons olive oil
- kosher salt and black pepper
- 1 1 1/4-pound piece skinless salmon fillet
- 1 tablespoon red wine vinegar
- 1 tablespoon whole-grain mustard
- 1 teaspoon honey
- 2 tablespoons fresh flat-leaf parsley, chopped
- Heat oven to 400° F. On a rimmed baking sheet, toss the potatoes, mushrooms, 1 tablespoon of the oil, and ½ teaspoon each salt and pepper.
- Roast, tossing once, until the potatoes begin to soften, about 20 minutes.
- Push the vegetables to the edges of the pan and place the salmon in the center. Season with ¼ teaspoon each salt and pepper.
- Roast until the salmon is opaque throughout, the mushrooms are tender, and the potatoes are golden brown, 12 to 15 minutes.
- Meanwhile, in a bowl, whisk together the vinegar, mustard, honey, and parsley, the remaining 2 tablespoons of oil, and ¼ teaspoon each salt and pepper. Drizzle over the salmon and vegetables before serving.