Extra-virgin olive oil for baking, plus 1/4 cup
1 baguette, sliced crosswise into 1/4-inch-thick slices
Salt and coarsely ground pepper, to taste
8 vine-ripened tomatoes, about 1 1/2 lb.
1/2 cup slivered fresh basil leaves
2 Tbs. finely minced red onion
1/4 tsp. minced garlic
1 Tbs. balsamic vinegar
1 1/2 lb. fresh mozzarella
Preheat oven to 350.
Brush a baking sheet with olive oil and arrange the baguette slices on the sheet in a single layer. Brush the tops with oil, and season with salt and pepper.
Bake until crisp and golden, 15 to 18 minutes. Cool to room temperature.
Core and seed the tomatoes and slice the tomatoes lengthwise into 1/4-inch-thick slices.
In a mixing bowl, combine the tomatoes, half of the basil, the onion, garlic, vinegar, the remaining 1/4 cup olive oil, salt and pepper and mix well.
Slice the mozzarella into 1/4-inch-thick pieces and, if necessary, cut into smaller pieces so they fit on the crostini.
To assemble, lay a piece of mozzarella on each crostini and spoon 1 to 2 Tbs. of the tomato salad on top.
Garnish each with a pinch of the remaining basil.