Baked Halibut Tomato Basil

I was standing at the fish counter, staring at the halibut fillets under the glass, when the vendor said they'd just come in that morning. Something about the way the flesh looked so clean and firm made me want to keep the preparation simple. I grabbed a basket of cherry tomatoes on the way out, and by the time I got home, I knew exactly what I wanted to do.

The first time I made this, I served it to friends who claimed they didn't usually like fish. They finished every bite and asked for the recipe before they left. One of them even texted me a photo the next week when she made it herself, and that felt better than any compliment.

Ingredients

• Halibut fillets: Choose fillets that are about the same thickness so they cook evenly, and make sure they're patted completely dry before seasoning or they won't brown as nicely.
• Olive oil: Use regular olive oil for brushing the fish since it has a higher smoke point, and save the extra-virgin for the relish where you'll actually taste it.
• Kosher salt and black pepper: Season generously because mild fish like halibut needs that boost, and freshly cracked pepper makes a noticeable difference.
• Lemon slices: They add moisture and a subtle citrus aroma while baking, and they look beautiful on the plate even if you don't eat them.
• Cherry tomatoes: Quartering them releases their juice into the relish, which mingles with the vinegar and oil to create a light, flavorful sauce.
• Red onion: Dice it finely so you get little pops of sharpness without overpowering the delicate fish.
• Balsamic vinegar: This adds a touch of sweetness and acidity that balances the richness of the olive oil perfectly.
• Garlic: One clove is enough to add depth without making the relish taste too pungent or raw.
• Fresh basil: Tear or chop it coarsely just before mixing so it stays fragrant and doesn't bruise or darken too quickly.

Instructions

Prep the Oven and Dish:

Preheat your oven to 400°F and lightly grease a baking dish with olive oil or line it with parchment paper. This keeps the fish from sticking and makes cleanup so much easier.

Season the Halibut:

Pat the fillets dry with paper towels, then brush both sides with olive oil and season with salt and pepper. Drying them first helps the oil stick and the seasoning penetrate.

Arrange and Bake:

Place the fillets in the prepared dish and tuck lemon slices on top and around them. Bake for 15 to 18 minutes, until the fish flakes easily with a fork and turns opaque in the center.

Make the Relish:

While the fish bakes, combine the quartered cherry tomatoes, red onion, extra-virgin olive oil, balsamic vinegar, garlic, salt, pepper, and basil in a medium bowl. Toss gently so everything gets coated but the tomatoes stay intact.

Serve:

Spoon the tomato and basil relish over the baked halibut fillets as soon as they come out of the oven. Serve immediately while the fish is hot and the relish is cool and fresh.

Save

There's something about the way the cool, tangy relish hits the warm, flaky fish that makes every forkful feel intentional. It's the kind of dish that makes you slow down and pay attention, even on a busy Tuesday night.

Substitutions and Swaps

If you can't find halibut, cod or sea bass work beautifully and cook in about the same amount of time. I've also used this relish on grilled chicken when I had leftover tomatoes, and it was just as good. For a little heat, add a pinch of red pepper flakes to the relish, it wakes everything up without being too spicy.

Serving Suggestions

I like to serve this with steamed green beans or a simple arugula salad dressed with lemon and olive oil. A glass of chilled Sauvignon Blanc or Pinot Grigio is perfect alongside, the crisp acidity echoes the relish and cuts through the richness of the fish. Sometimes I add a small pile of roasted baby potatoes on the side, and it turns into a complete, elegant meal without much extra effort.

Make-Ahead and Storage Tips

You can prep the relish up to an hour ahead and keep it at room temperature, just wait to add the basil until right before serving. The fish is best eaten fresh, but if you have leftovers, store them in an airtight container in the fridge and gently reheat in a low oven. Leftover relish is wonderful on toast or stirred into pasta the next day.

• Store cooked halibut and relish separately to keep the fish from getting soggy.
• Use leftover relish within two days for the best flavor and texture.
• Reheat fish at 275°F for just 5 to 7 minutes to avoid drying it out.

Save

This is the kind of recipe that makes you feel capable and calm in the kitchen, even when life feels hectic. I hope it becomes one of those dishes you turn to when you want something nourishing, beautiful, and easy all at once.

Recipe FAQ

→ What is the best way to bake halibut?

Preheat the oven to 400°F and lightly grease a baking dish. Season the halibut with olive oil, salt, and pepper, then bake for 15–18 minutes until it flakes easily with a fork.

→ Can I use other fish instead of halibut?

Yes, cod or sea bass are good substitutes that work well with the tomato and basil relish.

→ How is the tomato and basil relish prepared?

Combine quartered cherry tomatoes, diced red onion, minced garlic, chopped basil, olive oil, balsamic vinegar, salt, and pepper. Toss gently to mix.

→ What can I serve alongside this dish?

Steamed vegetables, a light salad, or a crisp Sauvignon Blanc or Pinot Grigio complement the flavors beautifully.

→ Is this dish suitable for gluten-free diets?

Yes, the ingredients used are naturally gluten-free, making it suitable for gluten-free diets.