Chop the tomatoes. Core 3 tomatoes and, if they're especially juicy, scoop out the seeds (this is optional, but will help prevent the bruschetta from getting soggy). Chop the tomatoes into ½-inch pieces, you'll have about 2 cups. Place in a medium bowl.

Make the tomato mixture. Coarsely chop ¼ cup packed fresh basil leaves and add to the bowl with the tomatoes. Add 1 tablespoon extra-virgin olive oil, 1 teaspoon balsamic vinegar, ½ teaspoon kosher salt, and ¼ teaspoon freshly ground black pepper, and toss to combine. Set aside.

Toast the bread. Arrange a rack in the upper third of the oven (about 5 to 6 inches below the broiling element), and heat the broiler to high. Wipe off the cutting board and cut half a baguette into ¾-inch thick slices (you'll have 12 to 14 slices total). Arrange the baguette slices on a baking sheet and broil, flipping once, until golden brown and crisp on both sides, 1 to 2 minutes per side (watch it carefully so it doesn’t burn).

Rub the toasts with garlic. Peel and halve 1 garlic clove. Gently rub the toasts with the cut sides of the garlic.

Brush the toasts with olive oil. Brush each toast with a light coating of olive oil (you’ll need about 1 to 2 tablespoons).

Top with tomatoes. Taste the tomato mixture and season with more salt and pepper as needed. Scoop the tomato mixture out with a slotted spoon and divide evenly among the toasts. Sprinkle with flaky salt, if desired, and serve immediately.