Position a rack as close as possible to the broiler element and preheat the broiler.
In a small serving bowl, combine the tomatoes, basil, sea salt, pepper, and 3 tablespoons olive oil. Set aside.
Lay the slices of bread on a baking sheet and drizzle with the remaining olive oil. Broil on both sides until golden and crispy, about 1 1/2 minutes per side.
Remove the bread from the oven and rub the crushed garlic on the toasted bread. Mince the remaining pieces of garlic and add to the tomato mixture.
Return the baking sheet to the broiler for 30 seconds. Transfer the toast slices to a large platter and serve immediately, with the tomato mixture alongside for guests to spoon over the toasts.