Tear the bread into large pieces, put it in a large bowl and soak it with cold water. They used to make panzanella with leftover homemade baked bread: it had a very different and better flavour and took a lot of time to soak up. Nowadays 5 minutes often would do. The bread will absorb the water like a sponge.
Slice the onion thinly and collect it on a little bowl. Soak it in cold water, to quench its sharp taste.
Chop the tomatoes and slice thinly the cucumber.
When the bread is soft, squeeze it removing all the excess water and crumble it with your hands into a large bowl.
Dress the bread crumbles with the well-drained onion, the chopped tomatoes, the sliced cucumber and the fresh basil leaves, torn roughly with your hands.
Season with salt and a few grids of black pepper, then drizzle generously with extra virgin olive oil. Finish with the red wine vinegar to taste: it will brighten the flavour of this bread salad, so don’t be stingy with it.
Set aside for half an hour in the fridge, then it’s ready to be eaten.