Preheat the oven to 200C/400F/Gas 6.
For the baked sea bream, stuff the cavity of the fish with the garlic, red chilli, onion (or leek), parsley and half of the sliced lemon. Put the fish on a baking tray and place the remaining lemon slices and thyme leaves on top. Pour over the white wine, drizzle with olive oil and cover with aluminium foil.
Bake for 10-15 minutes (depending on the size of the fish), or until the fish is cooked through.
For the spinach, new potato and parsley salad, heat a pan of boiling water and cook the potatoes for 10-15 minutes. Drain and place into a large serving bowl.
Add the baby spinach and parsley. Stir and season to taste with salt and pepper.
In a small bowl, add the olive oil, white wine vinegar and Dijon mustard and whisk to combine. Pour the dressing over the salad just before serving.
To serve, place the whole sea bream on a serving dish and serve the salad alongside.