Preheat the oven to 200°C.
Place the sea bass fillet onto a large square of greaseproof paper on a baking sheet.
Add butter, seasoning, lemon juice, and white wine, then fold the paper to create a sealed parcel.
Bake for ten minutes until the fish is just cooked and keep warm.
Mix herbs, olive oil, lime juice, tomatoes, and soy sauce in a small bowl.
Sauté the onion in olive oil until softened.
Reduce the white wine by half, then simmer with cream, lime zest, and seasoning for 3 minutes.
Serve the fish in the opened parcel with the salad and lime butter sauce.