This dish screams easy summertime dinner and takes advantage of peak tomato season. Juicy heirlooms are a bed for the fish and sweet cherry tomatoes are lightly charred to give the vinaigrette a subtle smoky flavor. Serve with grilled country bread rubbed with garlic, a crunchy salad or buttery corn on the cob for a memorable meal.
Arrange the sliced tomatoes on a large platter and set aside. Pat the skin of the halibut dry with a paper towel and then brush the fillets all over with olive oil. Season the flesh generously with salt and pepper.
Oil the grill grates and put the cherry tomatoes and fish skin-side down on the grill. Cover and let cook until the tomatoes are charred and starting to split, about 5 minutes, depending on the ripeness of the tomatoes and the heat from your grill. Cook the halibut until just cooked through, about 10 minutes. Transfer the fish skin-side down to the platter with the sliced tomatoes.
Put the cherry tomatoes in a blender, discarding the vine, and add the olive oil, vinegar, 1 teaspoon salt and several grinds of pepper. Blend until smooth, then stir in half the chives and basil. Spoon the tomato vinaigrette over the fish and tomatoes. Drizzle everything with some more olive oil and sprinkle with the remaining chives and basil. Finish with a sprinkle of flaky salt.