- With the rack in the middle position, preheat the oven to 120 °C (250 °F).
- Crumple the sheet of parchment paper and run under water to thoroughly moisten and soften it (see note). Set aside.
- In a large ovenproof skillet, brown the garlic in the oil. Let cool slightly. Add the wine, parsley, and vinegar and stir to combine. Place the cod fillets in the skillet and baste with the pan juices. Season with salt and pepper.
- Cover the fish with the parchment paper. Bake at 120 °C (250 °F) for about 12 minutes or until the fish is just cooked. Let rest for about 5 minutes.
- In a large skillet or wok, heat the oil with the pesto. Add the spinach and cook, stirring, until wilted. Season with salt and pepper.
- Serve the cod with the garlic and a little cooking liquid. Serve with the wilted spinach and a piece of whole-wheat baguette.
Moistened parchment paper placed on the fillets during baking allows the fish to be steamed.