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; season with salt and pepper or your favorite seasoning.
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 tablespoon thyme; season.
Sprinkle the salmon with the remaining 1 tablespoon thyme. Serve warm or at room temperature with the sauce (sauce is optional).