Toss Brussels sprouts with 1/2 tsp olive oil and bake at 425F until lightly browned, 15 to 20 minutes.
Coat salmon with 1/4 tsp olive oil or a thin layer of cooking spray (1-second spray) and season with 1/8 tsp each salt and pepper. Bake at 425F until salmon is opaque in the middle, 4 to 6 minutes. Serve Brussels sprouts, salmon and brown rice drizzled with the vinaigrette and topped with walnuts.