Position a rack 4 inches from the top of the oven and preheat the broiler for 7 to 10 minutes.
Line the bottom of a broiler pan with foil and coat liberally with nonstick spray.
Squeeze some lemon juice over each of the halibut fillets, then rub them with olive oil on both sides and season with salt and pepper.
Arrange the fish on the prepared broiler pan and broil for 4 minutes.
Carefully turn the fillets over and baste with some of the pan juices.
Return them to the oven and broil for an additional 4 minutes, until the fish flakes easily and is opaque all the way through.
Plate individual servings of fish, top each with about 1 tablespoon of the pesto and serve immediately.
Notes
If halibut isn't available you can definitely substitute another firm-fleshed fish like cod, grouper or haddock. Check out our Simple Guide to Broiling Fish for cooking guidelines.