Chop the parsley very finely and put in a bowl. Mix in the crushed garlic cloves and the bread. Season with salt and freshly ground pepper and wet with lemon juice. Set aside.
Rinse the fish under cold running water and pat dry with kitchen paper. Open the underside and fill the cavity with the herb and bread stuffing. Keep refrigerated.

Meanwhile prepare the vegetables. Top and tail the beans and cut into even sizes. Halve the cherry tomatoes. Remove the flowers from the baby marrows and wash well.

Remove the stamen and cut the flowers into strips. Top and tail the baby marrows and cut into matchsticks. Peel and slice the onion very finely.

Brush a large sheet of greaseproof paper with extra virgin olive oil and place the fish on it. Cover the fish with the vegetables and season with salt and freshly ground pepper and drizzle over some extra virgin olive oil. Seal the paper to form an airtight parcel and place in a steamer and cook for 20 minutes. Serve at once.