Preheat the oven to 425 degrees . On a rimmed baking sheet, toss the green beans, corn and tomatoes with the oil. Arrange in a single layer. Place the salmon in the center, skin side down; season with salt and pepper.
Roast until the vegetables are tender and browned in spots and the salmon is just opaque in the center, about 20 minutes.
Meanwhile, in a small bowl, mix the sour cream and 1 tbsp. dill; season.
Sprinkle the salmon with the remaining 1 tbsp. dill. Serve warm or at room temperature with the sauce.