Drizzle salmon with 1 tablespoon vinaigrette. Place on a broiler pan coated with cooking spray. Broil 3-4 in. from the heat for 10-15 minutes or until fish flakes easily with a fork. Cut salmon into two pieces.
Meanwhile, in a large bowl, toss spinach with remaining vinaigrette. Divide between two plates. Top with the salmon, avocado, walnuts, sunflower kernels and cranberries.