Step 1

In a medium bowl, combine the tomatoes, garlic, vinegar, a heaping ¼ teaspoon salt, and ⅛ teaspoon pepper. Set aside.

Step 2

Season the halibut all over with ¾ teaspoon salt and ½ teaspoon pepper.

Step 3

Heat 2 tablespoons of the oil in a 12-inch nonstick skillet over medium-high heat until hot and shimmering. Place the fish, presentation-side down, in the pan and cook, without touching, until golden brown and crisp, about 3 minutes. Flip the fish and lower the heat to medium; continue cooking until the halibut is just firm to the touch and opaque when you pry open a thicker piece with a paring knife, 3 to 4 minutes. Transfer the cooked halibut to a plate or serving platter.

Step 4

Add the remaining 1 tablespoon oil to the pan, followed by the cherry tomato mixture. Cook, stirring occasionally, over medium heat until the tomatoes start to break down and release their juices, a few minutes. Stir in basil, then taste and adjust seasoning if necessary.

Step 5

Serve the halibut filets with the cherry tomatoes spooned over top and alongside.