Tuscan fish tray bake

Name: Tuscan fish tray bake
Prep time: 15 min
Cook time: 45 min
Total time: 1 h
Cuisine: Italian
Ingredients: 1 red onion, halved, thinly sliced; 1 red capsicum, cut into 1cm thick strips; 2 tbsp extra virgin olive oil; 2 garlic cloves, crushed; 1 tbsp balsamic vinegar; 700g bottle Val Verde passata cooking sauce; 1/2 cup Sicilian olives; 1/4 cup chopped fresh basil leaves; 4 x 150g firm white fish fillets, skin on; Extra small fresh basil leaves, to serve; Crusty bread, to serve