Abruzzese-Style Panzanella

Classic panzanella, Tuscan bread salad, has few ingredients, just the bread, cucumbers, ripe tomatoes, and red onion. I’ve added tuna, which turns it into a one-dish lunch for two or three. It’s dressed with good olive oil and wine vinegar (and maybe a splash of balsamic), sea salt, and torn basil. You can punch it up with capers or olives, but on swelt…