Dice tomatoes, finely chopped raw garlic, and freshly chopped basil. Mix together, and put in a non-reactive bowl (plastic or ceramic). Cover with something airtight: saran wrap works great. Let sit at room temperature for at least 30 minutes (longer is better).
For the bread, brush thin slices with olive oil, then lightly toast in a hot oven. Heap the the tomato mixture on the bread, and serve.