Method 

If you’re using a barbecue, light it about 30 minutes before you plan to start cooking so that the charcoal has time to become cooking-ready (for more info, see our handy guide, Getting the Most from a Charcoal Barbecue ). Otherwise, pre-heat the oven to 200⁰C (180⁰C fan; Gas Mark 6). Brush the bread slices lightly all over with 1 tbsp of the oil and sprinkle over a pinch of salt and some pepper, then either grill on the BBQ for a few minutes per side until nicely charred, or place in the oven for 15 mins, turning halfway through, until crispy and golden. Tear the cooked bread into bite-sized pieces and place in a large bowl. Add the capers. 

Next, make the dressing; whisk together the lemon zest and juice with the honey, mustard and 2 tbsp of the olive oil, then season well with salt and pepper. Pour half of this over the bread and capers and toss to combine. 

Place a griddle pan on the highest heat, and cut each half-nectarine into 2 or 3 chunky wedges.  Place them in a bowl and drizzle over the remaining 1 tbsp oil, turning the wedges to coat. When the pan is hot, add the wedges and cook for a couple of minutes per side, until they take on nice char marks (or grill them on the BBQ), then add them to the bread bowl, together with the salad leaves, and rip in half of the basil. Add the remaining dressing and toss together, then transfer to a serving dish. Top with the mozzarella pieces, sliced prosciutto and the remaining basil leaves, then scatter over the walnuts (if using) before serving.