Preheat oven to 350F.
Slice French bread loaf and cube into 1-inch pieces (roughly 5-6 cups). Place on large, rimmed cookie sheet.
Drizzle 3 tbsp. of extra virgin olive oil over bread and toss to coat. Sprinkle a teaspoon of salt over bread cubes, tossing again to coat. Toast bread cubes in oven for 10-12 minutes or until golden brown, stirring a couple times during baking. Remove from oven and cool.
Prepare vegetables. Halve cherry tomatoes, salt them, and place in small collider to allow excess juice to drain. Chop bell peppers. Cut cucumber in half lengthwise and slice into thin slices. Cut onion into thin slices. Chop or tear basil into about ½ inch pieces.
To make dressing: in a bowl add garlic, Dijon mustard, and white wine vinegar, whisking until combined. Slowly pour olive oil into vinegar mixture, whisking constantly to make an emulsion. Add salt and pepper and whisk until incorporated.
In a large bowl, add cooled toasted bread cubes, cut vegetables, chopped basil, and capers, tossing to combine. Pour dressing over salad and toss to coat bread and vegetables.
Garnish with additional sliced basil if desired. Serve immediately after preparing.