Preheat the grill to medium heat.
In a small bowl, whisk together the olive oil, minced garlic, vinegar, ½ teaspoon salt and ¼ teaspoon pepper. Set aside.
Place the cucumbers, tomato, basil, capers, and shallots in a large bowl. Sprinkle with large pinch of salt and pepper.
Brush bread slices on both sides with olive oil and sprinkle lightly with salt. Toast them on the grill until golden, about 4 minutes on each side. A little black char on the edges is good! Cut a thin slice off the garlic clove and rub one side of each piece of bread with the cut side of the garlic.
Cut the bread into cubes and add to the cucumber mixture. Pour in the vinaigrette and toss to combine.