Trim the spring onions and fennel (reserving any leafy tops), peel the carrot, then slice them all ½cm thick. Halve the tomatoes. Peel and finely slice the garlic and chilli. Squash and destone the olives. Put a large frying pan on a high heat with 1 tablespoon of olive oil. Stir in the onions, fennel and carrot, followed 4 minutes later by the tomatoes, garlic, chilli and olives. Toss regularly for 2 minutes while you lightly score the fish on both sides (this will help flavour and heat to penetrate as it cooks).
Lay the fish on top of the veg, stuff half the herbs into the cavities, then pour over the wine and let it reduce by half. Add about 300ml of water, to come 1cm up the side of the pan. Cover and leave to thunder away on a high heat for 8 minutes (boiling underneath, steaming on top means fragrant veggies). Pick the remaining herb leaves, finely grate the lemon zest over them, then chop and mix together.
Uncover the fish and baste with its juices for 1 minute. To check the fish is cooked, go to the thickest part up near the head – if the flesh flakes easily away from the bone, it’s done. Remove to a plate, spoon over the veg and juices, drizzle with extra virgin olive oil, scatter over the lemony herbs, then squeeze over the lemon juice. Great served with bread to mop up that irresistible sauce, or with new potatoes, couscous or rice.