• Preheat the oven to 180C (350F).
• Slice the onions into rings and roughly slice the garlic.
• Chop the tomatoes into quarters and add to a Deep Large Roasting Tin with the onions and garlic.
• Drizzle over 3 tablespoons of the oil, season well with salt and pepper and stir to make sure everything is well coated.
• Bake in the oven for 45 minutes. After 45 minutes stir through most of the handful of chopped coriander (cilantro) leaves, leaving a few behind to stuff the fish with and garnish the dish at the end.

Prepare the fish

• Slice half of the lemon and stuff into the belly of the fish along with a few coriander (cilantro) leaves.
• Rub the tablespoon of olive oil all over the fish skin to coat it well and season well with plenty of sea salt.
• Lay the fish on top of the tomato and onion mixture and bake for a further 15 minutes until the fish is cooked through.

Optional step

• When the fish is cooked through, turn the grill on for a couple of minutes to crisp up the skin on the fish and char it slightly.
• Squeeze the juice of the remaining half a lemon over the dish and serve garnished with a sprinkling of the chopped coriander (cilantro) leaves.