Step 1

Preheat oven to 450°F. Toss together potatoes, herbes de Provence, pepper, 2 tablespoons of the oil, and 1 teaspoon of the salt on an 18- x 13-inch rimmed baking sheet. Arrange potatoes cut side down, and spread mixture evenly. Roast 10 minutes. Remove from oven.

Step 2

While potato mixture roasts, stir together mixed herbs, panko, mustard, and 1 tablespoon of the oil in a small bowl. Rub salmon evenly with 1 tablespoon of the oil, and sprinkle with ½ teaspoon of the salt. Spoon herb-panko mixture evenly over salmon, pressing to adhere.

Step 3

Add tomatoes to baking sheet with potatoes, and spread mixture evenly (leaving potatoes cut side down). Return to oven; roast at 450°F for 5 minutes. Meanwhile, stir together vinegar, garlic, and remaining 1 tablespoon oil and ½ teaspoon salt in a small bowl; set aside.

Step 4

Remove baking sheet from oven. Push potato-tomato mixture to outer edges of baking sheet; arrange salmon in center of baking sheet. Return to oven; roast at 450°F until salmon is just firm and opaque, about 12 minutes. Remove from oven. Spoon vinegar mixture over potato-tomato mixture, and stir to combine. Divide salmon and potato-tomato mixture evenly among 4 plates.