Place tomatoes in a large bowl. Cover with 2 tsp salt and mix well. Let tomatoes sit for 15 minutes, allowing them to drain excess moisture. After 15 minutes, discard excess water and pat tomatoes dry.
Meanwhile, heat olive oil over medium heat in a large pan. Add bread cubes and toast for 10 minutes, until golden brown. If pan gets dry or bread starts to burn, add more olive oil.
Mix dressing ingredients together in a small bowl and whisk until combined.
Combine tomatoes, bread, peaches, red onion, garlic, and arugula in a large bowl. Add dressing and toss, then let sit for 15 minutes before serving.
Serve with fresh basil.