- Pat halibut fillets dry with a paper towel and place in a bowl.
- In another bowl, combine garlic, lemon zest, lemon juice, and olive oil. Season with salt and pepper and mix to combine.
- Pour entire marinade over halibut fillets and cover with plastic wrap. Let fish marinate for at least one hour in the fridge.
- Preheat barbecue on high and oil grill.
- In the meantime, combine all salsa ingredients in a bowl. Set aside in fridge.
- Place fish on the grill. Barbecue on high for 3 to 5 minutes per side (depending on thickness) or until a meat thermometer inserted in the middle of the thickest part reads 63°C (145°F). Flesh should flake away easily.
- Arrange fillets in plates and top each fillet with salsa. Serve immediately.
For easier cooking, place fish on a grill rack with small holes placed directly on top of the BBQ grill.