01 - Preheat the oven to 400°F. Line a baking sheet with parchment paper or lightly grease it.
02 - Pat the halibut fillets dry with paper towels and place them on the prepared baking sheet.
03 - In a small bowl, whisk together 2 tablespoons olive oil, lemon zest, lemon juice, 1/2 teaspoon sea salt, and 1/4 teaspoon black pepper.
04 - Brush the olive oil mixture over both sides of each halibut fillet, ensuring even coverage.
05 - Bake for 15-20 minutes, or until the fish is opaque throughout and flakes easily with a fork. Thicker fillets may require additional time.
06 - While the fish bakes, combine cherry tomatoes, red onion, basil, extra-virgin olive oil, balsamic vinegar, minced garlic, 1/4 teaspoon salt, and 1/8 teaspoon pepper in a medium bowl. Toss gently and let sit at room temperature for 10 minutes to allow flavors to meld.
07 - Remove the halibut from the oven and transfer fillets to serving plates. Spoon tomato and basil relish generously over the top. Serve immediately with extra fresh basil and lemon wedges if desired.