Baked sea bass with romesco sauce

Name: Baked sea bass with romesco sauce
Cook time: 45 min
Total time: 45 min
Cuisine: Mediterranean
Ingredients: 4 red peppers , deseeded and cut into large chunks; 2 yellow peppers , deseeded and cut into large chunks; 2 large tomatoes , halved (choose on the vine for best flavour); 1 large red onion , cut into wedges; 4 large garlic cloves; 4 tbsp olive oil , plus extra for drizzling; 2 x 1kg/2lb 4oz whole line-caught sea bass , scaled and gutted; 2 lemons , thinly sliced; 2 large handfuls fresh mixed herbs (such as rosemary and thyme); 2 tsp balsamic vinegar; 50g whole hazelnut , toasted