Cook orzo in a medium saucepan according to package directions, omitting salt and stirring in peas after 7 minutes.
Meanwhile, place salmon on a foil-lined baking sheet and season with salt, to taste. Spread the salad dressing evenly over the salmon. Broil 4 inches from heat source 6–8 minutes or until opaque in center. Sprinkle half of the scallions over the salmon.
Drain orzo and peas; return to same saucepan. Stir in oil and remaining scallions, and season with salt and freshly ground black pepper, both to taste; serve with salmon.