Heat the oven to 180°C/160°C fan/gas 4. Score the sea bass skin and flesh several times on each side using a sharp knife, season with sea salt and rub with olive oil. Heat the grill to high, put the fish on an oiled, lipped baking sheet and grill for 5 minutes on each side until the skin is crisp and tinged with gold. Put in the oven and cook for 15-20 minutes. To test if it’s done, push a skewer into the thickest part of the fish, normally behind the head, then check the skewer is hot. Put the fish on a serving platter with a few lemon wedges.
Meanwhile, cook the broccoli in boiling salted water for 2 minutes then drain and pat dry. While the broccoli is cooking, heat a little olive oil in a medium frying pan and fry the garlic and chilli over a low heat for 2-3 minutes. Increase the heat and add the broccoli. Drizzle with a little more olive oil, add the lemon juice, season with salt and pepper, then toss well to combine for about 1 minute. Serve alongside the fish.