Preheat your oven to 400°F (200°C).
Cut the baguette into 1/2-inch thick slices. Place the slices on a baking sheet.
Toast the bread slices in the preheated oven for about 5-7 minutes, or until they are golden brown and crispy. Keep an eye on them to avoid burning.
In a bowl, combine the diced tomatoes, chopped basil, finely diced red onion, and olive oil. Season with salt and pepper to taste. Mix well.
Once the bread slices are toasted, remove them from the oven. Spoon the tomato mixture onto each slice, spreading it evenly.
For extra flavor, you can drizzle a little balsamic glaze over the bruschetta.
Arrange the bruschetta on a serving platter and serve immediately.