Thinly slice the onion, soak in boiling water for 1 minute, then drain.
Slice the tomatoes, layer them on a serving dish.
Peel off the skin of the grilled pepper, then cut the flesh into thin strips.
Scatter the onion slices, pepper strips, olives and capers on top of the tomatoes. Drizzle with 2 Tbsp of olive oil, then season with salt and pepper.
Drain and wipe the cheese with kitchen paper, then cut into 1 cm slices.
Brush them with some oil then barbecue or griddle them on both sides for 1-2 minutes.
Put the cheese slices on top of the salad, drizzle with the remaining oil and some freshly squeezed lemon juice.