Arrange bell peppers on a baking tray. Sprinkle salt and olive oil. Bake for 15 to 20 minutes at 200 C. Once baked put the bell peppers in cold water. Peel the pepper skin and slice them into thick chunks. Mix roasted and chopped onion and chilli in a bowl. Blend garlic cloves, red chilli flakes, fresh basil, and parsley leaves, oregano, red wine vinegar, salt, and olive oil to prepare the dressing for peperonata. Pour the dressing on the peppers. Mix with chopped parsley basil leaves, and roasted onion and chilli mix. Peperonata is ready. Halve an Italian focaccia bread. Arrange the pepperonata on each half. Garnish with grated Parmesan cheese and basil leaves.