1. Cut the salmon fillet into 6 equal portions, and lightly spray both sides of each piece with cooking spray. Sprinkle with dried thyme, salt, and black pepper.
2. In a large skillet, heat butter on medium-high until foamy. Carefully place the fillets in the skillet. Cook the salmon; don't move fillets until the edges begin to crisp, about 2 minutes. Decrease heat to medium, and cook until fish is golden brown, about 1 minute more. Turn fillets and continue cooking until medium-rare and skin is crisped, about 3 minutes, depending on their thickness. Remove fillets to serving plates and drizzle with balsamic vinegar.