Cook the soba noodles according to the package directions. Drain and run under cold water to cool.
Meanwhile, heat the oil in a large skillet over medium heat. Season the salmon with ½ teaspoon salt and ¼ teaspoon pepper. Cook until opaque throughout, 5 to 6 minutes per side.
Using a fork, flake the salmon into pieces.
In a large bowl, toss the noodles with the bell pepper, scallions, and vinaigrette. Transfer the noodles to bowls and top with the salmon.