
This whole baked sea bass is roasted over tender new potatoes and juicy cherry tomatoes, then finished with a bright watercress, herb, caper, and chili salsa. It is fresh, colorful, and impressive enough for guests while still simple enough for a relaxed dinner.
Preheat the oven to 220°C/200°C fan/425°F/gas 7. Put the sliced new potatoes in a large pan of salted boiling water and simmer for about 5 minutes, just until barely tender. Drain well and set aside.
Pat the sea bass dry, then make three shallow diagonal cuts on each side of the fish. Rub the fish with olive oil and season inside and out with salt and black pepper. Place 2 bashed garlic cloves and the lemon slices inside the cavity.
Spread the parboiled potatoes and cherry tomatoes in a baking dish and season lightly. Set the fish on top and roast for 20-25 minutes, or until the thickest part of the fish is opaque and flakes easily from the bone. Transfer the fish to a warm platter, cover loosely, and return the potatoes and tomatoes to the oven for another 10 minutes to finish roasting.
Meanwhile, make the salsa. Pulse the watercress, parsley, cilantro, chili, and capers in a food processor until finely chopped, adding a little extra-virgin olive oil as it blends. Stir in the remaining oil, the crushed garlic clove, and lemon juice, then season to taste.
Spoon the roasted potatoes and tomatoes onto a serving platter. Place the whole fish on top and drizzle generously with the watercress chili salsa before serving.
Ask your fishmonger to gut, scale, and remove the gills from the sea bass. If sea bass is unavailable, use another firm whole white fish of a similar size, such as branzino, snapper, or trout. Avoid overcooking the fish; it is ready when the flesh is opaque and pulls away from the bone easily. Leftover salsa can be refrigerated for up to 2 days and spooned over grilled fish, chicken, or vegetables.