Slice the tomatoes, or cut them into halves, quarters or wedges, depending to their shape and size. Put them in a large bowl and season generously with smoked salt. Cover and set aside for at least 30 minutes (longer is fine).
30 minutes to 2 hours before you plan on eating, toss the olive oil, vinegar and red onion into the tomatoes. Toast the bread until well charred and, once cooled, break large chunks into the salad. Toss well to combine, then transfer the salad to an airtight container and keep chilled until you go out.
Just before eating, add the peach wedges and scatter with the lavender flowers (if using), breaking the flowers slightly between your fingers as you go. Toss the salad well to combine, then drizzle over some honey; about 2 tsps should do it.